hello, I'm Judith, and new here.

Why do all of my cupcake shrink, or does my cupcakepaper become larger after I take my cakes out of the oven???

Have no idea ....

You could try baking the cupcakes at a lower temperature  (325) for a bit longer.  When they are taken out of the oven cupcakes are still baking inside while they cool off.

My cupcakes shrivel when I bake them at 350.  I have actually taken to baking jumbo cupcakes because they don't shrink, but of course, they use more batter and are rather large…