I appreciate you joining this thread, @Chris_Accounting_2023. Correcting the negative balance on your A/R aging report is essential to align invoices and collect payment on past due. I'll help you figure it out as we go along some steps.

If you see negative balances, it indicates that your customer has paid more than what you billed them. In this case, there might be open or unapplied payments that need to be accounted for due to the customer's overpayment status.

If there are no invoices, create one to apply the payment. It will remove the negative amounts from the A/R Aging report from your deposits. Once done, let's proceed to link it to the payment.

1. Press on +New.
2. Select Receive Payment.
3. In the Receive Payment window, choose a customer.
4. Enter the date when the payment was made.
5. Under the Outstanding Transactions section, put a check mark on the invoice you want to pay.
6. In the Credits section, select the credit or deposit.
7. Hit on Save.

Moreover, please review the payment date if it's not earlier than the invoice date. How you process the payment also affect your  customer's current outstanding balance. 
 

To give you more insights regarding managing customers overpayment in the system, feel free to check out this link: Learn what to do in QuickBooks Online when a customer overpays you.

I'll be around to help if you need further assistance. Have a good day.