I went back to arma after 2 years like you.
When first time used arma ad i was a bit lost a specially on new formula maps - first simple fortress and next advanced maps with strange additions makes me crazy.
Maybe it is good idea to change the initial settings in arma to use windowed mode in next releases. That will prevent any display problems on new installs and it is much easier to get than try guesing right resolution from config files.
My english suck but i hope i've said what i want