for the 7c go into the main menu, scroll up, and select the trainer option
now if you are useing a realflight sim cable the 4yf MUST be turned on (not sure about other sim cables but try turning it on anyways)
then on your 7c scroll up to the INH symble turn it, if should be able to change to off. if not your trainer cord connection may be bad/4yf not turned on/ect.
if it turns to off the left hand snap roll switch is now your trainer switch.

i forgot how to change it to pcm ill go check for you if you want