here is what Horizon hobby sent me for instructions
Thank you for contacting Horizon Hobby Product Support.

To set up duel elevators you will need to perform the following:

Input Select Menu: INH the AUX 2

Program Mix 5 or 6: MIX Elevator and AUX 2
Rates +100 up +100 down

Plug the right elevator in the elevator channel and left elevator in AUX
2 port on the receiver.

How do I get to the input section to INH Aux2? I can get both sides of the elevator to go in the same direction. Problem is: they both go down the same, but one will only go about 1/2 of the way up compared to the other side.