Pontiac 2005 Aztek Owner's Manual page 36

3. To make the lap belt longer, tilt the latch plate and
pull it along the belt.
1-30
To make the belt shorter, pull its free end as shown
until the belt is snug
4. Buckle, position and release the lap-shoulder belt the
same way as the other lap-shoulder belts. If the belt
is not long enough, see Safety Belt Extender on
page 1-35.
Make sure the release button on the buckle is positioned
so you would be able to unbuckle the safety belt
quickly if you ever had to.