you calibrated the trans in reflex the first time right?, now you go to assign keys, click on what you want to assign and make sure you center all the sticks, including the gyro gain put it at 50%

at the bottom of the assign screen you will see it ask you what to do like lets say you click on aileron, once you center everything it will ask you to please move the aileron to the right and hold it there, and it will config the channel automatically for you, then recenter everything for the next one and so forth.