How do I properly adjust the shoulder belt height for the driver's safety belt?

Before driving, move the shoulder belt height adjuster so the shoulder portion of the belt is centered on your shoulder, away from your face and neck but not falling off your shoulder. To move it down, push down on button (A) and slide the height adjuster to the desired position; to move it up, push up on the shoulder belt guide. After adjusting, try to move the adjuster down without pushing the button to confirm it has locked into position. (Page 47)