UK , where do I live!
But sometimes I find users laptops , even servers out of my timezone
Also there can be gpos blocking you to change the timezone! ( and the system just goes by the US time or European ! ). yes it does! other colleages of you could have set this wrong 😦
This will be highlisted
In resume . A quick fix until you find the heck GPO causing this …
Greyed.. out gents…

You now go to powershell … Admin mode ! and run this (UK ONLY)
Set-TimeZone "GMT Standard Time"
All the other timezone (NON UK, GMT) can be shown with the following other command:
Get-TimeZone -ListAvailable

I have updated a nice script that changes all for you ( 23 / 03 /2021 )
#Change date format
$culture = (Get-Culture).Clone()
$culture.DateTimeFormat.ShortDatePattern = ‘dd/MM/yyyy’
Set-Culture $culture
#Change timezone and region
#Set home location to United Kingdom
Set-WinHomeLocation 0xf2
#override language list with just English GB
$1 = New-WinUserLanguageList en-GB
$1[0].Handwriting = 1
Set-WinUserLanguageList $1 -force
#Set system local
Set-WinSystemLocale en-GB
#Set the timezone
Set-TimeZone “GMT Standard Time”
#Restart the OS