FORD 2003 Expedition v.4 - Manual (Page 169)

Third row adjustable head restraints
Your vehicle’s third row outboard seating positions are equipped with
head restraints which are vertically adjustable. The purpose of these
head restraints is to help limit head motion in the event of a rear
collision. To properly adjust your head restraints, lift the head restraint
so that it is located directly behind your head or as close to that position
as possible.
The head restraints can be moved
up and down.
Push control to lower head restraint.
Seating and Safety Restraints
169