2003 Buick Rendezvous Owner's Manual - Page 11

To raise the seat, pull up on the lever located on the front right side of the seat. You can lose control of the vehicle if you try to adjust a manual driver's seat while the vehicle is moving. The sudden movement could startle and confuse you, or make you push a pedal when you don't want to. Adjust the driver's seat only when the vehicle is not moving. To lower the seat, push the lever down. Adjust the seat and release the lever. 1-4