Hello there, @communityoil.
You can delete the payment and re-apply it to the invoice. Let me guide you how.
- Go to Sales, then select Customers.
- Find the customer's name.
- In the Transaction List tab, choose the paid invoice.
- Pick the 1 payment linked.
- Locate the date.
- In the Receive Payment page.
- Select More, then hit Delete.
- Push Yes to confirm.
For future reference, I’m adding an article that contains instructions on how to handle entries that were entered by accident: Void or delete transactions.
Additionally, the use the audit log to re-enter deleted transactions article provides an overview of how to restore deleted data.
Please let me know if you need anything else. I'll be around to help you some more. Thanks.