What to do when there are no clear moves?

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I agree with this.

I agree with what knewyawker said, tr and look for weaknesses e.g. hanging pieces and break down their defence

I agree with this.
Even though it amounts to saying "to play good moves, you play moves that are good"
It doesn't explain anything.

When you can't defend, create an attack. You don't need to wait for the other player to blunder for you.

I have this same problem, I can find a lot of tactics, but I often times simply don't know how to play most positions.

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Read my posts in this thread:
GM Larry Evans' method of static analysis - Chess Forums - Chess.com
It's about how to assess a position and form a plan.

I agree with this.
Even though it amounts to saying "to play good moves, you play moves that are good"
It doesn't explain anything.
It could, then again, there are some people that really don’t know.

When in doubt, sac the rook:
https://www.chess.com/game/live/73849348431

I can teach you EXACTLY how to think during the game (opening, middlegame and endgame). Your chess understanding will never be the same and you will improve a lot. I charge €10/h, but if you can’t afford too many lessons, don’t worry. I can teach you a lot in an hour. Here to help if you are interested.
If you want to study by yourself, read ‘Logical Chess’. It is really instructive book. You have it on youtube as well: https://www.youtube.com/watch?v=0eTB7oHeRgM&list=PLUrgfsyInqNa1S4i8DsGJwzx1Uhn2AqlT

I would say try to make a plan and think about what you need to do to achieve your goal. Could be setting up an attack, or as you say improving the position of your worst placed piece. Knowing how to improve the pieces position requires you to understand the strengths/weaknesses of the piece. This would lead to moving a knight to an outpost/advanced square once other pieces are developed, or moving a bishop to an open diagonal/making an open diagonal for the bishop to occupy.
These are the sorts of things you should think about when you do not know what to do next.

True, try to find weaknesses in your opponents pieces or try to find vulnerable squares; another suggestion, and one of the guiding principles of positional chess is to simply find a better squares for your pieces or one of your pieces. Simply, improve your position. Move your bishop where it can have more mobility, move your knight where it can commence an attack or defend a piece, place your rook on an open file or a file that will soon be open, and best of all, try putting your pieces where you can eventually overload against a well fortified position. It's not easy, and patience is the key.

let me give you a positon where it seems very unclear
here you can take a couple minutes to come up with a plan as white, take as much time as needed in a game of chess to find a plan, a plan here is that you could could expand on the queenside, or you could target the weak doubled pawn, or try to play f3-e4 to break everything