This setting can de-activate itself if you are not in memory mode (1-2-3 modes on the seat).
To activate it just put your foot on the brake, put the car in reverse gear. Whilst in reverse gear, manually tilt the passenger side mirror down all the way with the mirror 'mini joystick' control on your door panel.
Now, when you put the car into neutral, drive or park, the mirror should tilt back to its normal position. When you put the car in reverse the mirror should tilt down.
Once you have set all positions of seat, steering wheel adjust and mirror save that in one of the memory postions.
Try it and let me know.