From the owner's manual: (www.motorcraftservice.com -> owner guides)
Saving a Passive Setting
The vehicle stores the seating and mirror
positions for up to three remote controls
or passive keys. Next time the vehicle is
unlocked, the position of the seat and
mirrors will adjust to the last used position.
Each time you turn the ignition off, the
current seat and mirror settings are stored
on the remote control or passive key used.
Passive Recall
Note: If more than one passive key is in
range, the memory function will move to the
settings of the first key stored.
When you unlock the vehicle with the
remote control or pull the driver door
handle with a passive key in range, the seat
and mirrors will move to the position stored
on that remote control or passive key.