Welcome to the Community.

Thanks for joining this thread. I can provide clarifications about adding custom fields on invoices.

Yes, the tailored fields automatically apply to new invoices. To associate the past entries with the custom fields, manually open each one and select the proper template.

The defined-fields will not show on the report if they’re added as columns on an invoice. Add them to the customer’s profile so they'll appear on the statement.

Here's how:

1. Go to the Customers menu at the top to choose the Customer Center.
2. In the Customers & Jobs tab, right-click beside the customer's name to access its profile.
   
3. Tap the Additional Info menu on the left panel to choose the Define Fields button.
   
4. In the Set up Custom Fields for Names window, enter a term that will identify the field.
   
5. Click OK to save the changes.

The newly created custom field will show on the Invoice's page. From there, manually enter the information you want to appear on the transaction.

For additional information, check out the Create and use custom fields in QuickBooks Desktop article. It provides an overview of how to track custom name and item fields.

Let me know if you need assistance while working in QuickBooks. I’ll pop right back in to assist further. Enjoy the rest of the day.