Where is it?
Top BLUE TAB on your store and Go STORE
MANAGE STORES and Go to the store you want and click MANAGE
Pick CONTENT and Go to Edit Content
From the Menu on your left and Go to DESIGN MIGRATION
This feature will copy your current designs from one product and place them onto newly released products. This will happen immediately following the release of a new product, and does not include designs created after the new product release. Notice on the second option it includes "royalty cap." In the future Zazzle will have a royalty cap on some products if the Zazzle partner wants that.