Good day, TammieMB. 

I'll guide you on how to create a refund in QuickBooks Online.

We can create a check in QuickBooks to record the refund, reduce your bank's balance, and offset the customer's overpayment.

Here's how:

1. Click on + New.
2. Choose Check. You can also switch to Accountant view first if you're in Business view, then come back to these steps.
3. Select the customer you want to refund from the Payee ▼ dropdown.
4. From the Payment account ▼ dropdown, select the bank account where you deposited the overpayment to.
5. On the first line of the Category column, select Accounts Receivable.
6. Enter the amount of the refund in the Amount field.
7. Complete the other fields as you see fit, then select Save and close.

Once done, we need to link the refund to the customer's overpayment.

Like this:

1. Click on + New.
2. Choose Receive payment.
3. Select the same customer you used for the check or expense when recording the refund.
4. Complete the other fields as you see fit.
5. Under the Outstanding Transaction section, tick the checkbox for the Check you created when recording the refund.
6. Make sure the payment is equal to the open balance, then select Save and close.

For more details about the refund process, check out this link: Record a customer refund in QuickBooks Online.

I've added this article if you need to print the refund check: Print a check in QuickBooks Online.

Let me know if you have other concerns or questions about processing the customer refunds. I'll get back to you as soon as possible. Keep safe!