Cursor in editor moves to center as screen is enlarged

Just started—again–with Scrivener for Mac, this time version 3. Here is my problem: When I am in Scrivener with the screen minimized, the cursor, or caret, in the editor pane is where I like it, at the far left. When I go to full screen on the Mac (not Composition mode) the caret moves to the center; the margins are huge so the whole editor screen is not used. If I manually enlarge the screen, the caret slowly moves to the center. Can I get some help with this please?

I found the problem. I was using the fixed width setting. Turned that off and now it’s set the way I like it. Thanks to anyone who has been thinking about this.