On my Futaba 7C, I have to turn the trainer function on. I can also choose what channels they are able to use (In the menu, the channels they can use are "F", and the ones they can't are "N"). Also, if you have the trainer switch assigned to a snap roll, the switch won't work for the trainer feature. If you do have a snap roll assigned to the trainer switch, the trainer feature will not change from INH to OFF. Just turn the snap off (INH), and turn the trainer option from INH to OFF (ON when the switch is pulled). I hope the 6EX and 7C are similar enough that this does the trick.