This parameter is selected when creating a fingerprint and cannot be changed later. In this case, your working screen will correspond to the selected resolution. In short, if your desktop resolution is 1280x1024, and when creating a print you specify 1920x1080, then it will not disappear into your screen and it will not be very convenient for you to work. Likewise, if you choose a resolution lower than yours, you will work in windowed mode.
IMPORTANT: Do not maximize the screen. The fingerprints are created so that sites cannot understand that you are working with an emulated fingerprint, and think that this is a real device.