Oh wait, nevermind, the option for Run as Administrator isn't available for the filetype. My bad. Well, are you still not able to save the file at all?
The file should be able to remain a .cfg file that opens with the Notepad program, yes. If it still shows .cfg as the file type, then that is fine. For example, my .cfg files changed to a notepad icon but they are still a .cfg file. As long as you didn't save it to a .txt file you should be good to go! That is, if it does end up saving.