I appreciate all the efforts you've gone through to fix your login issue to QuickBooks Desktop, @rjlane. But don't worry, I want to ensure this issue is taken care of, and I'd like to redirect you to the best support group available to get this addressed right away.
With all the troubleshooting steps shared by my colleagues above, you should be able to fix your login issue. Since it didn't work, I recommend contacting our QuickBooks Support team again. I understand that you've contacted them before, but they're the best group who can further check on this matter. They can also provide in-depth troubleshooting steps to get this resolved and create an investigation if other users are experiencing the same.
To reach them, you can follow the steps provided by my colleague MaryJoyD above.
You may also want to manage your user's login in QuickBooks Desktop. This article will guide you through the process: Create and manage users and roles in QuickBooks Desktop.
Come back to this post and let me know how it goes, @rjlane. I'll be around to help.
