QuickBooks Online (QBO) doesn't currently have a store credit option, but you can use a credit memo to record and apply returns for a Customer.

Creating store credits in Syncro adds a credit memo inside your QuickBooks account. Store credit does not get deposited into an account until it is applied to an Invoice. Once the credit is added to your QuickBooks account, the credit memo disappears from Syncro.

To sync store credits to QuickBooks:

1. Navigate to the QuickBooks Settings page in Syncro (add quickbook/settings after yoursubdomain.syncromsp.com in your browser's address bar).
2. Scroll to and check the “Sync Store Credit to QuickBooks” box. 
3. Enter QB Item names for both Store Credit Gifts and Unmapped Products in a Customer Purchase, then click Save QuickBooks Settings.

Here is an example of a credit memo in QuickBooks prior to being synced to Syncro:

Tip: After syncing to Syncro, you can find this credit memo listed under https://yourdomain.syncromsp.com/payments.