Let's move the customer payment from an invoice to a different one, @judy65.
If the payment you're applying is under the same customer, then you can move it.
- Go to Sales tab and then proceed to the All Sales tab.
- Filter the type of transaction for Money received, then select Apply.
- Select the payment you want to move.
- In the Received Payment page, put a checkmark to the right invoice, then uncheck the incorrect one.
- Click Save and close once you're done.
If it is a payment linked to a different customer, then follow the steps in this article: How to fix a payment applied to the wrong customer invoice.
Here's also a detailed guidance on how to record invoice payments in QuickBooks Online.
I'm always here if you need more help in applying payments to your invoices. Take care and have a great rest of the day!