Hello, @drrcnegex.

The billing address on the invoice always follows the information recorded on the Customer  Information page. You can update the billing address displayed on a specific invoice. However, it will revert back to the original address when you create a new invoice for the same customer.

Here's a screenshot on how it should look like on your end:

To isolate the odd behavior you've experienced, you can create a dummy customer with a dummy invoice. Once completed, create and save an invoice with a different billing address. If the address of the sample invoice reverts back to the original one you've entered, let's perform some troubleshooting steps.

      1. Access your Use an incognito or private browser to access your QuickBooks Online account:

             > Google Chrome, press CTRL  + Shift + N

             > Mozilla Firefox: press CTRL  + Shift + P

             > Internet Explorer: Press CTRL  + Shift + P

             > Safari: press Command + Shift + N

      2. The stored information and history in your regular browser may affect QuickBooks' performance. If you’re able to save an invoice with a modified billing address, you may want to clear its cache.

     3. Delete and recreate the invoice you're having an issue with.

     4. Enable Active Scripting (if using Internet Explorer):

          a. From the Tools menu, select Internet Options.

          b. Click the Security tab and select the Internet icon.

          c. Click Custom Level.

          d. Select Enable under Active Scripting.

          e. Click OK twice.

     5. Reset the browser to its default settings.

Meanwhile, to learn more about fixing unexpected browser-related behaviors, you can check these articles:

• Troubleshooting browser problems
• QuickBooks Online doesn't load correctly or has blank pages

Feel free to leave your comments below if you have other questions. I'm always here to help.