Hello cstolovitz,
I hope you are doing well this weekend! I wanted to share some information in regards to creating a refund receipt inside of QuickBooks Online and it comes with a great video tutorial as well:
Create Refund Receipt
https://quickbooks.intuit.com/ca/tutorials/create-refund-receipt/It also goes over on how you can revisit the refund receipt once you have completed the transaction.
I hope this helps, let me know if I if you still require assistance, I'd be more than happy to assist.
Kindest Regards,
Lourdes Fernandez