Shirley Corriher, in her book - Cookwise, also says the beading is due to overcooking.
Try cooking it at a higher temperature for a shorter period of time. To prevent shrinkage, make sure you spread the meringue onto the crust all around the pie. That gives it something to hold onto so it won't shrink back.
I put the hot filling into the crust then immediately add the meringue to the edge and bake. The meringue will cook faster if it's put onto a hot filling.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan