I appreciate you joining the thread, Christee. I want you to know that the solution provided above relates to QuickBooks Online (QBO) users. I'll show you how to include your customer's outstanding balance in QuickBooks Desktop (QBDT).

You can add the past due amount to your current invoices in QBDT by following these steps:

1. Open your company file.
2. Go to the Lists menu, then Templates.
3. Look for the invoice template, then select Edit Template.
4. Tap on Additional Customization from the Basic Customization window.
5. Mark the box beside Customer Total Balance and/or Job Total Balance.
6. Hit OK to save the changes.

Here's an article you can open that'll give you detailed instructions about modifying form styles in QBDT: Use and customize form templates.

After that, try to record a new invoice to see the result. I'm adding this article as your guide: Create an invoice in QuickBooks Desktop. Also, learn more about the different ways in tracking customer transactions from this link: Get started with customer transaction workflows in QuickBooks Desktop.

Let me know in the comment section below if you have other QuickBooks questions. I'm always here to help. Have a good one!