How do I fix a paid invoice that is showing up as a negative entry?

Allow me to share some information regarding the negative entry on your sales, fishnetltd5-gmai.

The negative amount is from the overpayments or credits. You'll have to check if these are duplicates or not. Then, check if there should be an invoice to apply it to. Create one if needed.

Apply the credit to an invoice you already created:

1. Click + New in the left panel and choose Receive payment.
2. Select the customer, then the credit and the invoice.
3. Select Save and New or Save and Close.

Apply the credit to a new invoice:

1. Click + New. in the left panel and choose Invoice..
2. Create the invoice.
3. Tap + New and select Receive payment.
4. Select the credit and then Save and Close.

You can visit this write-up: Clear up customers with zero net balances in the Accounts Receivable Aging report. It contains more details on how to deal with customers' zero net balances.

Swing by anytime if you have any questions. I'd be happy to help. Have a great rest of your day!