Make? Model? Year? What kinda car?

Psychic Wednesday isn't until next week.

There are pretty much 3 types of seatbelt (well, 4 if you count the
old manually-adjustable ones)

1) you pull it out, when you stop pulling, it locks and you have to
retract it fully if you want to make it longer

2) you pull it out slow, it runs out free. You pull fast, it locks,
but then unlocks when you retract it a little.

3) pull slow, fast, no difference, but when the setbelt mech. senses a
sudden motion of the vehicle, it locks. My ranger has this style and
it will lock over stutter-bumps.

You need to find out which style you're supposed to have- try playing
around with the passenger side belt.

Dave

Nowadays, they mostly give you belts that let you move a little, as
long as it isn't too fast. The fact that you say the drivers belts in
all the cars let you do so suggests that in the other cars, the
mechanisms are locking. They get pretty gummed up, living in the
interior. My gripe is with the ones that go the other way, and refuse
to take up the slack. Seems sort of dangerous.

Best slack taker up is the one in the New Beetle (don't know if they
still have this, it was in them when they were New); the belt was
attached to a tiny Wankel engine that had a couple of blank cartridges
sort of plumbed in where the spark plugs would go; when the impact
sensor decided you had smashed into something, it fired the cartridges
and the thing reeled the belt back in and pinned you into the seat. Is
that cool or what?