phartron
ok, I played with your file - the problem is that you are asking for fullscreen Centered.
Your layout is 1920 x 1080, but your screen isn't that resolution. So, it is giving you the layout you are asking for and then centering it in what is available.
I have two monitors in front of me - one is 1920 x 1080 (and that works the way you want), the other is 1280 x 1024 (and it looks very similar to what you are getting).
So, you need to choose one of the stretch settings if you want your game to fit any screen. If you need the full 1920x1080 then choose Stretch letterbox scale - but you will get black bars if the screen is a different resolution that can't be evenly stretched to fit. If you want to use the whole screen without black bars then you should choose Stretch scale outer - BUT you wont get 1920x1080 if the game is running on a monitor with a different resolution, which means it is up to you to make sure everything adjusts to use the space available!