What are you trying to adjust. You will probably have to make all the subtrims to zero. Then pull the servo horn off and turn on the transmitter then off to get the servos some what centered. Then put the horn back on so it is close to 90 degrees to the servo. Then go back to the subtrims and adjust that so it is exactly 90 degrees to the servo. Double check that the servos move the right way after all that is done!