Hello, lisakeith.
I know how to filter invoices that were saved with a negative amount.
To do this, you can run a Custom Transaction Detail report and customize it to display only invoice transactions.
Here's how:
- Go to the Report menu.
- Hover your mouse to Custom report, then select Transaction Detail.
- Set the correct date.
- Click Customize button, then go to the Filter tab.
- Select the TransactionType from the Filter section, then choose Invoice from the Transaction Type dropdown.

- Once done, hit OK.
- Double-click the invoice with a negative amount in the Balance column to open the transaction.

- Make necessary changes to the invoice and then click Save & Close.
For more information on customizing your reports, see this article: Customize reports in QuickBooks Desktop.
Also, you can memorize your report to save the current customization setting if you want to use it in the future. Memorize a report.
You're welcome to post again if you need anything else. We're always here to help you.