Perhaps also check possibilities under
(rightclick >) Options > Preferences > General (>General settings).
In the lower half (grey area) in the middle you can set resolutions under
"At start switch to" respectively "For full screen mode switch to".
Perhaps the second option is something for you?
[To be frank: I don't think it will make any difference to you as this option as well as the one you earlier found under Video "Change resolution" simply change the resolution of your monitor in Windows, so that in fact nothing will be changed in view of the fact that - most probably - you're already using such resolution.] 
Therefore I would certainly try out pan-scan options as earlier indicated as those options may well be what you're really looking for.