To add a credit or an order of a not-yet shipped or it has shipped, you have the option to apply that credit to an invoice and re-sending it to your customer.
Navigation: Search > Enter the order ID
- Bring up the order you want to apply a credit
- Click Unlock
- Scroll to the bottom of the page, under Credit Note enter a comments (optional) and amount.
- Scroll back to the top of the page, Enter Reason for Editing
- Click Save Changes