Reverse the servo direction by "switching wires" requires to modify the potentiometer wiring inside the servo; this means re-soldering each servo you want to reverse, you will have to modify both. There are few tutorials in YouTube. High risk of damaging the servo... it is deep waters.
The solution proposed by Andrew is IMO the best way to do it. Use the mix radio function to reverse servo direction. You only need to reverse one channel and keep using the Y cable
Below is the link for OrangeRx T-SIX manual
https://cdn-global-hk.hobbyking.com/...1444783X13.pdf
Another option could be just flipping the servo and the servo arm, instead of pushing it will be pulling. It might require some modification to the servo bay and relocation of the flaps horns.