That's assuming you're on WinXP. Most people seem to be these days but there's still a few old has-beens like me on Win98/Me. In this case fs9.cfg will be in this location. C:\WINDOWS\Application Data\Microsoft\FS9
If you're on XP you might need to change the folder options to "Show Hidden Files" or you won't see it. Once you find fs9.cfg, take my tip & create a Shortcut to it. Paste it to your Desktop for next time.
PS. All this & more useful information is posted in a sticky topic at the top of this forum index.
http://www.simviation.com/cgi-bin/yabb/YaBB.cgi?board=COF;action=display;num=1080212396