vascoboy, From the main Phoenix screen I believe you need to select System>YourControls> ...

Then Select your Tx model then Select Edit profile. On this Edit Profile screen find the column labeled 'invert'... Find your aileron channel (Look for Controller channel #2 below) and put a check in the 'invert' column to reverse the aileron controls... Click Finished to save your changes. I think you will be good to go...