resolution issue on my macbook

[matt.]

after starting the game the first time it was not in perfect resolution (top and right border did not fit to display). So I increased the resolution (to maxímum) and restart the game. After restart the resolution is worse and I can see only a small snippet of the game. At least the resolution increased but didn't scale with display...
The main problem is that I cannot change the resolution option because it is out of my display. I tried with different resolutions of my retina display.
I also checked the config.xml, but it contains no paramter for resolution.
Further I tried to reinstall the game (delete via steam and install again). It was also not working.
Somebody any idea how I can reset the resolution???

Cheers!