GMC 2008 Yukon Denali Owner's Manual page 50

CAUTION:
{
A safety belt that is not properly worn may not
provide the protection needed in a crash. The
person wearing the belt could be seriously
injured. The shoulder belt should go over the
shoulder and across the chest. These parts of
the body are best able to take belt restraining
forces.
1-46
4. Buckle, position, and release the safety belt as
described previously in this section. Make sure
that the shoulder belt crosses the shoulder.
To remove and store the comfort guide, squeeze the
belt edges together so that you can take them out of the
guide. Slide the guide into its storage clip on the
interior body or storage pocket on the side of the seat.