If it's not working precisely this way, then try adjusting the 3 pots... I can't remember what pot does what, some experimenting for you to do.
And do this esc calibrating with the gimbal chs (throttle/rudder).
Once it does work properly, then put for/rev rx lead into Aux 3 and steering rx lead into Aux 1 or 2 (your choice), then tell me what happens.
