P196 in the PDF manual, although I guess page may vary across the different types/editions of manual. Was in 1-7 "Adjusting the angle of the outside rear view mirrors".
Linked mirror function when reversing (vehicles with driving position memory)
When the mirror select switch is in the “L” or “R” position, the outside rear view
mirrors will automatically angle downwards when the vehicle is reversing in order to
give a better view of the ground.
To disable this function, move the mirror select switch to the neutral position (be-
tween “L” and “R”)
With the shift position in R, adjust the mirror angle at a desired position to set the
mirror angle used when the vehicle is reversing.
The adjusted angle will be memorized and the mirror will automatically tilt to the
memorized angle whenever the shift position is shifted to R from next time.
The memorized downward tilt position of the mirror is linked to the normal position
(angle adjusted with the shift position in other than R). Therefore, if the normal
position is changed after adjustment, the tilt position will also change.
When the normal position is changed, readjust the angle in reversing.