Buick RIVIERA 1993 Manual page 16

Seats and Seat Controls
Power Seat
Front Control (F): Raise or lower the front of the seat
by holding the switch to the right or left.
Center Control (C): Move the seat forward or back by
holding the control to the front or back. Raise the seat
by holding the control to the left. Hold the control to the
right to lower the seat.
Rear Control (R):
Raise or lower the rear of the seat by
holding the switch to the right or the left.