To print UPC Numbers on order copies, the option needs to be checked in two places.
The first can be found by going to Options then Edit Preferences.
On the Printing Options tab, make sure the Print UPC Numbers on Order Copy box is checked, then remember to SAVE!
The second place it needs to be checked is when you go to preview an order, from Order Entry. click Preview on the right, and check the box that says Print UPC Numbers, and that's it!