GMC 2018 Acadia Denali Owner's Manual page 54

The height of the head restraint can
be adjusted. Pull the head restraint
up to raise it. Try to move the head
restraint to make sure that it is
locked in place.
To lower the head restraint, press
the button, located on the top of the
seatback, and push the head
restraint down. Try to move the
head restraint after the button is
released to make sure that it is
locked in place.
The second row head restraints are
not removable.
Folding the Second Row Head
Restraint
The head restraint can be folded
rearward to allow for better visibility
when the rear seat is unoccupied.
To fold the head restraint, press the
button on the side of the head
restraint.
Seats and Restraints
The head restraint will fold rearward
automatically.
When an occupant or child restraint
is in the seat, always return the
head restraint to the full upright
position. Pull head restraint up and
forward until it locks into place.
Push and pull on the head restraint
to make sure that it is locked.
Always adjust the head restraint so
that the top of the restraint is at the
same height as the top of the
occupant's head.
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