Welcome back to our forums, @Lisa-S,

Allow me to join the conversation and add a bit more about correcting customer overpayments in QuickBooks.

You're almost there you only need to take more steps. Since you issued a refund check to the client, you'll need to link the transaction to the Accounts Receivables account. Let me walk you through the steps:

1. Locate the refund check.
2. Go to the Expenses tab then add Accounts Receivable in the Account column.
3. Make sure the refund amount is correct by clicking the Recalculate button at the top of the transaction.
4. Click Save & Close.

This is how it should look like:

Once done, find the invoice then link the refund to offset the overpayment. Follow the steps below:

1. Click the Customers menu, then choose Receive Payments.
2. Add the customer name in the Received from the drop-down.
3. Tap the Discounts And Credits icon at the top.
4. In the Available Credits section, mark the check you created, then hit Done.
5. Select Save & Close.

That should rectify the issue, @Lisa-S. Here's a great article I've added for your reference: Record a credit memo or refund in QuickBooks Desktop

I want to ensure that you're able to enter your refund without any issues, so please feel free to let me know how it goes. I'll be keeping an eye out for your response. Have a good day!