I notice that you don't put them on their tops to cool down.
My Grandma taught me to always do that. Seemed to have far fewer "snaping" of the tops. You know, when you press down on the lids if they pop up and down they are not sealed yet. These have to be either reprocessed or eaten sooner or put in the fridge.
My sister and I always wait till they have "set" before putting a label on them. If firm, they are "jam or jelly or conserve" and if
runny, they are labeled "Pancake Syrup".