To access the refund and store credit information on Shopify back office:
Log in to your shopify back office.
On the shopify dashboard click on the order tab on the top left side.
Search or scroll to find the order you need information on.
Click on the order. It opens the order page.
Scroll down to the timeline section on the page.
Click on the comment regarding refund and store credit.
You will get detailed information including the amount and the store credit code.