Refunds are only available if there is an issue with;
The item - such as a tear on a t-shirt, or a mug being broken in transit. Or the wrong size being sent by the printer. (this does not cover your customer selecting the wrong size)
The print - the design is not the design they chose, or there is a misprint.
Shipping - the item has not arrived, or has been lost in transit.
Your customer deciding they don't like the item any more, or wanting to make changes that deviate from the original purchase are not covered.
You should read the terms and conditions before requesting a refund. You should think about offering a reprint to your customer, before offering a refund.
If you still need to request a refund for one of the orders from your Shopify store, click here to open the refund request form.