Simple question, for my DX7 with Slow Stick, I have left stick for throttle,
and use right stick for rudder/elevator. Is this okay? Someone told me today that left stick should be throttle/rudder and right for elevator/aileron and always left this way. Why? Also way I have it I can use left stick for zoom on my camera for AP. Thanks

It's really up to you but your friend is right about the lay-out for mode 2. Personally I would learn mode 2 so you can fly other planes in the future or let others fly yours.

That is fine.

you are using a "modified" version of Mode II.

True Mode II = aileron and elevator on the right. Since you have no ailerons... then having the rudder on the right is normal.

Actually... there is no wrong way to arrange the controls as long as it works for you. The problems that can come up all have to do with when other people try to operate your plane. (or when programming mixes if you get REALLY strange about the setup)

Thank you that ans. my question.

In Mode 2, the left-right axis of the right stick is used for your primary turning control surface. So for a 3-channel plane without ailerons, that's the rudder.