Set up a condition where you have some offset in the AFR for the flap channels. When you go into the AFR section, you can see the mode, which is set to EXP1, EXP2, or POINT. To the right of that is the offset. Just adjust it a bit up or down, and your flap channels will then re-center to the offset position you set. Make sure the AFR is set to "SINGLE" on the second page where the heading is "Group".