The car memorizes both settings forward AND reverse, put the car in reverse and setup your mirrors as you like, next time you put reverse will go to the position previously set.
However.... and this is my personal experience... I would like to have 2 reverse settings.
Moving forward I need only one position but...
When I go in reverse I would like to have one setting to see the curb that I currently have, however the mirrors are so tilted down that are useless to see around the car (not in the back of the car since the camera is great for that).
And another setting to see around the car to know if I'm going to hit another car with the bumper or a tree in the sidewalk.
Note: my car doesn't have park assist since the option was not available at that time.