Why does the player settings for a project not override previous default resolutions?

Hey everyone :-)

So I have a weird problem with the build settings for my projects.

Essentially, say that I create a new project. If I go and change the player settings and uncheck "Default is Full Screen", and set a new default screen width and height for, say, 800x600 and then build and run the game the settings will be correct.

However... if I try to change these player settings subsequently, for example by changing the default resolution to 1440x900, then it will simply keep the old 800x600 resolution no matter what I do. I've try to hunt down temporary build files in the project folder for the build, I've tried naming the build .exe with a different name, and even tried building the project to a completely different folder. But nope, it keeps the settings that I used for my very first build, and all resolution settings I change after that simply aren't applied. It is very annoying.

Does anyone have any idea what is going on here? :-)

Thank you all very much!