I'm still tryin to pick-up on this Canning lingo. I used the glass jars.

For some reason I had one that didn't seal? after I removed all the jars from the canner and set them on the counter, I could hear them "pop" as they were sealing up. All but one of them made this "pop" so I checked and and sure enough, no seal. Are you really suppose to crank that ring down tight or are these lids suppose to seal themselves??