I watch video lessons on Youtube. But only some of the moves stick. So I watch them again and again till it sticks. Every once and a while I'll set up a board and play as much of the theory I can. Just to see how much I can remember.
How to learn openings
uhh, I saw that one. I have mac and I really wouldn't want to install something on my pc anyway. Is there something similar online?

I found it helpful to learn opening principles. Then, the reason you play openings a certain way makes more sense and they can stick better.

A mistake I've made is to be a bit narrow in looking at openings. Rather than get a more specified book, better to get something like "fundamental chess openings" or "mastering the chess openings". Go through a few of them learning just the first dozen moves and maybe a few variations to see what suits you. At our level, you'll see early inaccuracies rather than theory - both against AI and human opponents. When you encounter inaccuracies (books don't cover them), figure them yourself and with analysis then write them down in a notebook.

I would strongly recommend learning basic opening principles before trying to learn any specific opening. Once you have masted and intuitively use the basic principles whenever you play, learning individual openings and theory will be a lot easier (and likely make more sense).
At the risk of pumping my own tires, I've created a free course on Chessable that covers all the basic principles, as well as common opening tactics and instructive annotated games. It may be exactly what you are looking for, and the price is right: https://www.chessable.com/smithys-opening-fundamentals/course/21302/
"... [Fundamental Chess Openings by Paul van der Sterren] is not particularly suited for players who are just starting out. I would imagine players rated at least 1400-1500 would get the most benefit from this volume. ..." - FM Carsten Hansen (2009)
https://web.archive.org/web/20140626173432/http://www.chesscafe.com/text/hansen128.pdf
http://www.jeremysilman.com/shop/pc/FCO-Fundamental-Chess-Openings-76p3561.htm
http://www.gambitbooks.com/pdfs/FCO_Fundamental_Chess_Openings.pdf
"... I can strongly recommend Mastering The Chess Openings: Volume 2 to all chess players from 1800 on up." - IM John Donaldson
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-2-76p3570.htm

Chess Openings Resources for Beginners and Beyond...
https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond
"... For beginning players, [Discovering Chess Openings] will offer an opportunity to start out on the right foot and really get a feel for what is happening on the board. ..." - FM Carsten Hansen (2006)
https://web.archive.org/web/20140627114655/http://www.chesscafe.com/text/hansen91.pdf
Once one has chosen openings, I think that there is wide agreement that the way to start is by playing over sample games. Some of us think that it can be useful to use books like First Steps: 1 e4 e5 and First Steps: Queen's Gambit
https://www.newinchess.com/media/wysiwyg/product_pdf/7790.pdf
https://chesscafe.com/book-reviews/first-steps-1-e4-e5-by-john-emms/
https://www.newinchess.com/media/wysiwyg/product_pdf/7652.pdf
as sources of games with explanations intended for those just starting to learn about an opening. Be sure to try to use the openings in games in between sessions of learning. Most of the time, one faces a position with no knowledge of a specific move indicated in a book. One has to accept that as part of chess, and think of opening knowledge as a sometimes helpful aid. After a game, it makes sense to try to look up the moves in a book and see if it has some indication of how one might have played better in the opening. Many opening books are part explanation and part reference material. The reference material is included in the text with the idea that one mostly skips it on a first reading, and looks at an individual item when it applies to a game that one has just played. Resist the temptation to try to turn a book into a mass memorization project. There are many important subjects that one should not neglect because of too much time on opening study.
https://www.chess.com/article/view/how-to-understand-openings
https://www.chess.com/blog/HanSchut/understand-your-opening-using-tabiyas-pawn-structures-model-games-and-typical-tactics
"... Overall, I would advise most players to stick to a fairly limited range of openings, and not to worry about learning too much by heart. ..." - FM Steve Giddins (2008)
"... I feel that the main reasons to buy an opening book are to give a good overview of the opening, and to explain general plans and ideas. ..." - GM John Nunn (2006)
"... If the book contains illustrative games, it is worth playing these over first ..." - GM John Nunn (2006)
"... the average player only needs to know a limited amount about the openings he plays. Providing he understands the main aims of the opening, a few typical plans and a handful of basic variations, that is enough. ..." - FM Steve Giddins (2008)
"... Everyman Chess has started a new series aimed at those who want to understand the basics of an opening, i.e., the not-yet-so-strong players. ... I imagine [there] will be a long series based on the premise of bringing the basic ideas of an opening to the reader through plenty of introductory text, game annotations, hints, plans and much more. ..." - FM Carsten Hansen (2002)
https://web.archive.org/web/20140627055734/http://www.chesscafe.com/text/hansen38.pdf
"The way I suggest you study this book is to play through the main games once, relatively quickly, and then start playing the variation in actual games. Playing an opening in real games is of vital importance - without this kind of live practice it is impossible to get a 'feel' for the kind of game it leads to. There is time enough later for involvement with the details, after playing your games it is good to look up the line." - GM Nigel Davies (2005)
"... Review each of your games, identifying opening (and other) mistakes with the goal of not repeatedly making the same mistake. ... It is especially critical not to continually fall into opening traps – or even lines that result in difficult positions ..." - NM Dan Heisman (2007)
https://web.archive.org/web/20140627062646/http://www.chesscafe.com/text/heisman81.pdf

HI, I'm searching for a way to learn opening. Just going through them is not helpful as I don't remember them. And for playing with someone else I already should know them to avoid stupid mistakes and time waste.
Are there any ways to practice different openings to remember them better?
"I'm searching for a way to learn openings."
Find the openings you like, and learn the basic ideas behind the piece placement, and pawn structure. Why do the pieces and pawns go where they go? Blindly memorizing moves without understanding t he "why" behind the moves isn't learning.
"Just going through them is not helpful as I don't remember them."
Thats because memorization without understanding isn't learning. You can read a bunch of books on brain surgery, but that doesn't mean you are a brain surgeon.

A site which offers a unique interactive, online approach to training and courses on openings, (and chess in general) is Chessable.com. It is very popular.

"... I can strongly recommend Mastering The Chess Openings: Volume 2 to all chess players from 1800 on up." - IM John Donaldson
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-2-76p3570.htm
Nope. Literally own the book volume 1 and was reading it tonight. Perfectly comprehensible.
Solving the same problems repeatedly at the beginning of each game over the board is just daft, unnecessarily confusing, and a waste of clock time.
Well, here are some reviews and samples:
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-1-p3569.htm
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_1.pdf
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-2-76p3570.htm
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_2.pdf
https://web.archive.org/web/20140627115737/http://www.chesscafe.com/text/hansen99.pdf
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-3-76p3571.htm
https://web.archive.org/web/20140626220240/http://www.chesscafe.com/text/hansen117.pdf
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_3.pdf
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-4-76p3572.htm
"... This series is written in such a way that anyone rated from 1500 to 2400 will be able to benefit from it. ..." - FM Carsten Hansen (2010)
https://web.archive.org/web/20140627070808/http://www.chesscafe.com/text/hansen137.pdf
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_4.pdf
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"… Note that Watson's series does not attempt to provide coverage of every opening, although it does treat the vast majority, in varying degrees. And of the openings it does deal with, there is no attempt to provide complete or comprehensive coverage. This series is more concerned with explicating ideas, themes and plans of the openings in general, and the analysis is impressive (IMO) for its depth and clarity. The author's point is not to cover the same ground that is detailed adequately and ad nauseum in the hundreds of other openings books which are concerned primarily with the 'theory' (i.e., the variations and lines) of specific openings. ..." - RussBell (June 5, 2018)

by repetition , a good example would be bobby fischers approach , where he would obsessively go over games even whilst in the bath . this gave him the solid classical approach that made him possibly the greatest chess player ever but im a Tal fan so he is better imo , but the masters don't stumble onto good openings they work hard to memorise them , as if you aint got your opening theory sweet you aint gonna get a good midgame endgame generally
HI, I'm searching for a way to learn opening. Just going through them is not helpful as I don't remember them. And for playing with someone else I already should know them to avoid stupid mistakes and time waste.
Are there any ways to practice different openings to remember them better?