Changing from case pack to individual unit

Hi all, I am trying to send a shipment to FBA but all of my SKUs are stuck on case pack as the packing type. I make one of a kind jewelry items. All of my jewelry is package in 4"x4"x2" boxes and each box weighs about 3oz. I want to send a shipment of 20 different SKUs in one shipping box. I can't figure out how to change each of my SKUS to packing type: individual units. And my SKUs are all asking for a new packing template but that does not give me the option there to change to individual units. Any help would be appreciated.