Hi there, @jjlNiche. Allow me to chime in on this thread.
It's not possible to auto-populate your existing customer's address to your imported invoices in QuickBooks Desktop (QBDT). However, there are two ways to proceed with this.
The first is to include the addresses in the template before importing it, and the second is to edit the imported invoices within the program manually.
Please note that even if you leave the Address column blank, you still need to add Address as a header since it's part of the template.
Moreover, creating a backup copy before making any changes to your company file is essential to ensure you have the original data to restore in case of data loss or damage.
Once you've sorted this out, you can now record the invoice payments of your customers after receiving them.
Let me know if you have further questions or concerns about importing in QBDT. I'm always here to help. Have a great day!