SOLVED: Group Policy Editor user preferences regional settings are underlined in red and cannot be changed and do not apply
When using Group Policy Editor to change the user preferences > regional settings you find these settings are underlined in red and whilst you can change them they do not apply when you click OK / Apply. Going back into the regional settings you find the settings have reverted to the default. To resolve this issue press F5 on each tab you want to edit and the control will underline in green. For more information about this see the following Microsoft article https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc754299(v=ws.11) While you're here - Why not check out our Group Policy Audit and Documentation Tool ?