Phone cases

Greetings,

Can anyone tell me where the button is for phone cases right on my art work site? The button is not by the rest of the printing options. I can only go to Products and then I get all phone cases. Isnt there a way to get exactly the case I want? Also, can I edit where the iphone image will be located on the phone case? Some of the images are in areas that are not good and I would love to move the images so it fits better on the phone case/
Thank you for your help.
Cecilia Brendel