Hi, when i launched your game, i immediately went to the settings to see what i could adjust, and to turn off the annoying faux Exclusive Fullscreen mode, so i can instead use some other tool to make the game use a good frame limiter (cause the game tries to render 600fps, wasting power and making my CPU run at 90%), and above that, so i can make the window use Borderless Windowed Fullscreen so the game won't annoyingly autohide whenever some notification or the start menu overlaps it, as for performance and behaving well, making it use a good dxgi flip model with maybe multi-plane overlay will make the game perform as well covering Windowed the entire screen or partially(with MPO) as it does with Exclusive Fullscreen. Futher, game could just pause when window is inactive.
However, the Fullscreen switch doesn't do anything. I can remove or add the checkmark, regardless what i set, after restart of the program, it will always be checkmark'ed again.
As for Resolution, while it has been set to Fullscreen, attempting to switch the resolution will not result in Windows (and as such the GPU or monitor) changing resolution. The game probably still tries to reduce rendering resolution so things look blocky or blurry(yes, i expect that if you scale a low resolution content to cover screen of higher resolution display), but what also happens is if the aspect ratio of the resolution differs slightly, black bars are introduced and part of the UI can not be touched (it's cut off), so since the game doesn't scale to be within the black bars, sometimes i won't be able to touch the three striped return button in the upper left corner.
Of course, best is still to play at native resolution with similar aspect ratio as display.
Speaking of the return button in the settings menu, while it may be a bit normalized for developers to use that in Android for settings menu's in the corner within apps, on Windows it's more rare, so maybe it's just me, but i had to figure out for a few seconds how to exit the settings menu or while inside a level since it wasn't obvious from a glance how, might be helpful to add a text or maybe change that button into an arrow or cross.