In Microsoft Cloud products the source of language configuration isn’t always consistent. Loop on the web uses the language preference from “My Account” or the Entra ID account.
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It is the property preferredLanguage in the Entra ID account…,
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…customizable via PowerShell and Microsoft Graph.
$Body = @"
{ "preferredLanguage": "de-CH" }
"@
Import-Module Microsoft.Graph.Authentication
Connect-MgGraph -Scopes User.ReadWrite
$Url = "https://graph.microsoft.com/v1.0/users/<UserPrincipalName>"
Invoke-MgGraphRequest -Method PATCH $Url -Body $Body -ContentType "application/json"
After making the adjustment, synchronization between products may take some time. Re-logging accelerates the process.