09 May 12, 06:57AM
Not sure how it works with Windows and i don't think it will fix your problem but i (Mac) can change it in the Assaultcube Launcher, if you can't then you can put this in you autoexec.cfg:
scr_w 840
scr_h 524
(change it to whatever size you want)
scr_w 840
scr_h 524
(change it to whatever size you want)