(C# unity) Buttons move when importing to android, what should I do?

Question

2D

In the unit, everything shows fine, the buttons are on the edges, there is a background.
When I start the game, I see this:

Answer 1

The fact is that you didn’t set up the canvas for different types of screens, because you tested the game on your computer and launched the finished build on the phone where the screen extension is different, then everything “broke” for you.
I highly recommend learning about canvas and its UI scaling system.

Answer 2

Look, go to your Canvas, there will be Canvas scaler / Canvas UI scaler and select Scale screen with size there. The problem must be solved.