And just for the record, I've played zero rated games on this account so...
You can't be higher than a rating that doesn't exist.
Your previous accounts had ratings. Not very high
"Very high" is relative.
For example, relative to you, they were "very high" 
nerves a butter. that names going onto my web page as best u/n's 
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...just put it in. yee !! L<3
I can't remember much but with lots of practice you diversify.
I trained myself to remember 9 moves of theory, I think I can remember more than that though.
I remember 13 moves of theory in the KID
You'll find you play a small range of openings often and begin to understand the various options within these and you'll feel comfortable playing them
I can't seem to remember more than two moves for the openings I've tried playing. It seems like there are infinite possible ways, and I can't remember which move is the best against my opponent's move. How did you get past this point, or is this a noob query?
This is a natural question to ask.
Memorizing all possible moves isn't a good approach; even modern chess engines are very far from brute force calculation to "solving" chess; there are too many possibilities. 10 to the 43rd power (10^43) is a "1" with 43 zeroes after it and this is the estimated number (Shannon Number) of possible legal chess positions. Obviously, the number of possible games would be massively larger; even if computers could calculate and evaluate all of this, there isn't the technology available to store all of this information.
Top chess players, like titled players, learn patterns and themes and these help them navigate the position to find the best moves. This is called "pattern recognition" and this skill gets refined with experience, lots of chess playing and lots of chess tactics/puzzles. The more patterns you expose yourself to, then the more likely you are to find these same ideas in a chess game 
[removed; spam/troll comment; DS]
I struggle with that for many openings. I am getting better in some and not in others. The ones I am getting better at I am memorizing guide games and analysising the games as well. Just building up over time.
I disagree with post 2. Good players do memorise many entire games.
Chess.com is best
The more you play, the more familiar you become with the patterns in your chosen openings.
And just for the record, I've played zero rated games on this account so...
You can't be higher than a rating that doesn't exist.