Hello, @pennees. Thanks for raising your concern in the Community and for performing troubleshooting steps. Let me provide you with additional instructions to disable automatic updates on your QuickBooks Desktop (QBDT).

Since the option to turn off automatic updates is grayed out once it's activated, you can resolve this by uninstalling and then reinstalling QBDT.

If the issue persists, you can delete the contents of the folder where QB stores waiting patches and then deny write permissions to the folder. Here's how:

1. Open QBDT.
2. Navigate to the Help menu and select Update QuickBooks Desktop.
3. Open the Options tab to find the folder listed under the Download Location section.
4. Use your desktop file manager to locate the folder.
5. Delete the contents of the folder (not the folder itself).
6. Right-click on the folder and select Properties.
7. Click on Security, then choose Edit to modify permissions.
8. Deny Write permissions for the Everyone and System users.
9. Hit the Apply button to save the changes.

Following these steps will prevent QB's ability to update itself automatically or manually from the Help menu.

If you ever wish to manually update your QBDT and access the latest features and product improvements, refer to this article for guidance: Update QuickBooks Desktop to the latest release.

I'm still ready to back you up if you have any other QBDT-related concerns. Feel at ease to add a reply to this thread. Take care and have a great day!