2012 GMC Sierra Owner's Manual - Page 71

Seats and Restraints Rear Seats The rear seat has adjustable headrests in the outboard seating positions. The height of the headrest can be adjusted. Pull the headrest up to raise it. To lower the headrest, push down on the headrest. Rear outboard headrests are not designed to be removed. 3-3 Front Seats Seat Adjustment { WARNING You can lose control of the vehicle if you try to adjust a driver seat while the vehicle is moving. The sudden movement could startle and confuse you, or make you push a pedal when you do not want to. Adjust the driver seat only when the vehicle is not moving. To adjust the seat: 1. Lift the bar under the front edge of the seat cushion to unlock the seat. 2. Slide the seat to the desired position and release the bar. 3. Try to move the seat back and forth to be sure the seat is locked in place.