I have a client that paid 3 different invoices from one invoice. QB states they have a credit. I can not figure out how to apply that credit to the two other invoices.

Thank you for reaching out to us, @JMPSJeff. I'd be glad to guide you in applying customer credits effectively in QuickBooks Online (QBO).

Here's how:

1. Go to +New, then click Receive Payment.

2. Choose your client's name.
3. In the Outstanding Transactions, select the boxes of the open two open invoices.

4. Under Credits, check the box to apply the credits to your invoices.
5. Once done, click Save and close.

Additionally, for reference on how to refund a customer, visit this article: Record a customer refund in QuickBooks Online.

If you have any additional questions or concerns about applying customer credits in QuickBooks Online, please feel free to tag me on thread.