Changing flight number/call sign without reloading a/c?

Usually when flying multiple legs the flight number changes from leg to leg. Is there a way to change the flight number (or even call sign) without reloading the aircraft when you're parked at an airport in between legs? Any workarounds for this?

Tried saving a flight with the default 737 with some switches thrown about and engines off, open up the .cfg file, typed in a new flight number and loaded the saved flight. Seemed to work, the flight number changes but the panel resets ie the panel state in the saved flight prior to .cfg edit isn't saved.

Thanks for your help.

Ned.