Click , then run restart64.exe (found in the CRU folder) to apply the changes. GPU Control Panels (NVIDIA/AMD/Intel) :
: Right-click the desktop, open NVIDIA Control Panel, go to Change resolution > Customize > Create Custom Resolution . Enter (Horizontal) and (Vertical). Stretched Res Pack For 768x500
: Edit options.txt and look for overrideWidth:768 and overrideHeight:500 . Click , then run restart64