RC2 has known problems with setting a different default compiler. If I remember correctly (90% sure) then this was fixed a few months ago.
As said in my last post, RC2 saves its configuration to the Windows registry, therefore you will not find any config files.
You may want to try a nightly build, they are at least as stable as RC2 and offer by far better functionality in every respect. Make sure you delete the old installation before unpacking the nightly build, or else you may run into dll conflicts.