Chevrolet 1994 Blazer Owner's Manual page 37

Pull up on the latch plate to make sure it is secure.
On four-door models, when the shoulder belt is pulled out all the way,
it will lock. If it does, let it go back all the way and start again.
If the belt is not long enough, see "Safety Belt Extender" at the end of
this section.
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.
To make the lap part tight, pull down on the buckle end of the belt as
you pull up on the shoulder part.
The lap part of the belt should be worn low and snug on the hips, just
touching the thighs. In a crash, this applies force to the strong pelvic bones.
And you'd be less likely to slide under the lap belt. If you slid under it, the
belt would apply force at your abdomen. This could cause serious or even
fatal injuries. 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.
1-25