rex_mate, not positive I understand your dilema. Possible you simply need to resize the screen so it's full screen?
Hover your cursor over the short edge until it becomes a double ended arrow. Drag it to the spot you like (do the same with other borders if needed). Exit the page using the option found under 'file' rather than the handier 'X' (only needs to be done once). That forces Windows to 'remember' and use the settings on subsequent boots.
HTH
Ed in Texas
If your display is a CRT and the image is distorted, your horizontal deflection amplifier may be failing.