Keyboard layout keeps changing and can't delete one?

I have factory reset my MacBook pro m1 2020, because i'm coding a lot on my laptop I have made a custom keyboard layout, that I have use previously. Now I added my custom keyboard layout to my keyboard inputs. When I use apps in windowed mode I can use the layout, but when I open programs in fullscreen it changes my layout and I can't change it. And the layout that I don't want to use, can't be delete. Tried to click on the - icon, but it doesn't do any thing.

Is there any other ways to delete a layout, so I can just have one, or a way to just use one layout.