In a Microsoft Exchange Server 2016 environment, consider the following scenario:
You have root and child domains in Active Directory.
You have Exchange Server 2016 installed in the root domain.
In this scenario, when a user in a child domain logs into Outlook Web App (OWA) and tries to change language by selecting Settings > Options > General > Region and time zone > Language, and then selects the check box next to Rename the default folders so their names match the specified language, the language can't be changed, and the default folder names mismatch the specified language.
This issue occurs because the finding user account function doesn't scan the whole domain forest after the user changes the language.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminology that Microsoft uses to describe software updates.