Unapplied Payment (Old payment)

Yes, the unapplied payment will be credited to the new invoice, panda0210.

You can set QuickBooks to apply credits automatically to a new invoice. Here's how: 

1. Go to Settings ⚙, then Account and Settings.
2. Select Advanced.
3. From the Automation section, click Edit, and select Automatically apply credits.

If you want to manually apply the credit to the new invoice, here's what you need to do.

1. Select + New, then select Receive payment.
2. Mark the invoice and the credit.
3. Click Save and New or Save and Close.

If a customer accidentally overpaid you, you can give a refund. Or if the customer paid more than the total balance on purpose, you can record it as a tip.

Let me know if there's anything else you need about the unapplied payment. I'm always around here in the Community Forum to help manage your customer's transactions.