Up to 2 attachments (including images) can be used with a maximum of 524.3 kB each and 1.0 MB total.
Unfortunately you are unable to change the image once a shirt goes live. Best option is to delete current shirt, create a new listing with your updated design.
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UK MERCH and Other Markets Expansion Suggestions
Tier Upgrade, simply a waiting game?
Why doesn't amazon send an email when people get tiered up?? It would be helpful and could be very encouraging
When is the 2018 Freeze planned to go live?
10 Tier but over 200 sales