Hello there, TammieMB.

Thanks for getting back to us and considering following the steps shared by my colleague. I'm joining here to help you process your customer refund with a check in QuickBooks Online.

First, we'll need to void the sales receipt paid by credit card. Here's how:

1. Go to the Sales menu.
2. Select All Sales.
3. Open the sales receipt you want to void. 
4. Click More. Then, Void.
5. Hit Yes to confirm.

Next, since the customer paid you with a credit card, we can create a refund right from the sales receipt. The steps below will guide you through the complete steps.
 

1. Still, go to the Sales menu. 
2. Within All Sales, find and select the sales receipt.
3. In the footer, select More, then Refund.
4. A refund receipt opens with all of the information from the customer form automatically filled in, such as payment method, the refunding account, and customer details. Verify that everything looks correct.
5. In the Payment method field, make sure to choose Check or the correct one.
6. Click Save and close.

The other way around is going to the +New button and select Refund receipt. For additional details, please check this article: Void or refund customer payments in QuickBooks Online.

Lastly, the resources below help you manage your customer's data and company's income:

• Record a customer refund in QuickBooks Online
• Sales and customers.
• Add, organize, and send invoices.

Feel free to post another one if you have more concerns about recording transactions in QuickBooks. We're all right here to help. Take care and have a good one!