Cant change resolution size of build/exe

I wrote a code for console that takes a string from the user and removes duplicate letters and vowels from it, creating a phrase that can be used for creating a sigil. I tried converting it to a unity 2d app/game, so I could easily add UI elements, so it looks like this:

The code works, and i changed the resolution size so it wont be fullscreen, but when I open the exe file it looks like this:

The game is still in fullscreen, and for some reason the size of the UI elements in the scene chages. If anyone can tell me what's going on here and how to fix it it'll be really appreciated ^^