
Microsoft has a habit of trying to default to US English and timezones whenever possible, which is obviously not ideal. In order to change this there are quite a few different places that need to be updated.

## Windows OOBE and unattend.xml settings

Firstly, when provisioning a new machine, ensure the ISO is of the correct language, and the unattend file (if being used, which you should be!), is setup to choose the correct languages and keyboard on first install. For a UK machine, this will look similar to this:

```xml
<component name="Microsoft-Windows-International-Core-WinPE" processorArchitecture="amd64"
    publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"
    xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <SetupUILanguage>
        <UILanguage>en-GB</UILanguage>
        <WillShowUI>Never</WillShowUI>
    </SetupUILanguage>
    <InputLocale>0809:00000809</InputLocale>
    <SystemLocale>en-GB</SystemLocale>
    <UILanguage>en-GB</UILanguage>
    <UILanguageFallback>en-US</UILanguageFallback>
    <UserLocale>en-GB</UserLocale>
</component>
```

```xml
<settings pass="oobeSystem">
    <component name="Microsoft-Windows-International-Core" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
    <InputLocale>0809:00000809</InputLocale>
    <SystemLocale>en-GB</SystemLocale>
    <UILanguage>en-GB</UILanguage>
    <UserLocale>en-GB</UserLocale>
    </component>
</settings>
```

These two segments can be added to your final XML file.

The language codes and keyboard codes can be found [here](https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-8.1-and-8/hh825682(v=win.10)).

## Post provisioning settings

Once the machine is provisioned, you can also use the following powershell script to change the language and keyboard settings:

```powershell
# Windows 11 and later
Install-Language en-GB -CopyToSettings
Set-Culture en-GB
Set-WinSystemLocale -SystemLocale en-GB
Set-WinUILanguageOverride -Language en-GB
Set-WinUserLanguageList en-GB -Force
Set-WinHomeLocation -GeoId 242

Copy-UserInternationalSettingsToSystem -WelcomeScreen $True -NewUser $True
```

The language codes and keyboard codes can be found [here](https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-8.1-and-8/hh825682(v=win.10)).
A list of geoIDs can be found [here](https://learn.microsoft.com/en-us/windows/win32/intl/table-of-geographical-locations).

For users on an active directory, the following attributes can be set to change the language and keyboard settings:

```powershell
Set-ADUser -Identity $user.SamAccountName -Replace @{
    'c' = 'UK';
    'co' = 'United Kingdom';
    'countryCode' = 826;
    'preferredLanguage' = 'en-GB';
    'msExchUserCulture' = 'en-GB'
}
```

Country code is an ISO 3 digit numeric code, a list can be found [here](https://docs.dnb.com/partner/en-US/iso_country_codes).

## Office 365 settings

365 timezones are used for things like showing relative time to other users, calender events, etc. The timezone can be set with the following powershell script:

```powershell
$timezone = "GMT Standard Time"
Connect-ExchangeOnline

$mailboxes = Get-Mailbox -ResultSize unlimited
$totalMailboxes = $mailboxes.Count
$currentMailbox = 0

$mailboxesUpdated = 0

Write-Host "Processing $totalMailboxes mailboxes"
$mailboxes | ForEach-Object {
    $currentMailbox++
    Write-Progress -Activity "Processing Mailboxes" -Status "Processing mailbox $currentMailbox of $totalMailboxes" -PercentComplete (($currentMailbox / $totalMailboxes) * 100)

    $calendarConfig = Get-MailboxCalendarConfiguration -Identity $_.Identity -WarningAction SilentlyContinue
    if ($calendarConfig.WorkingHoursTimeZone -ne $timezone) {
        Set-MailboxCalendarConfiguration -Identity $_.Identity -WorkingHoursTimeZone $timezone
        Write-Host "Updated calendar timezone for $($_.PrimarySmtpAddress)"
        $mailboxesUpdated++
    }
}

Write-Host "Updated $mailboxesUpdated mailboxes"
```


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