I'll attach a screenshot to guide you, M for TF.

We're unable to recommend any income account. The account used in my screenshot is manually created. I'll show you how to create one:

1. Click Accounting, then go to Chart of Accounts.
2. Click New.
3. Select the Account and Detail Types.
4. Enter a desired name.
5. Click Save and Close. 

As always, you can confer with your accountant on the best way to categorise the refund.

If there's anything else we can do, please let us know.