Changing the default screen width doesn't do anything

I’m doing the Space Shooter tutorial and when I try to change the default screen width to 600 width by 900 height, it doesn’t change anything. I tried changing the background to standalone and it helped a little bit, but it’s not at the width/height it is in the tutorial. The annotations don’t seem to say anything about this.

If you’re trying to change how wide the camera is, you can indirectly change this by changing the camera’s orthographic size (assuming the camera is in orthographic mode, which it usually is for 2D projects). This actually effects the height, but depending on your window size, it’ll also change how much you can see left and right