-
In classic Outlook, select File > Options > Language.
-
In the Office display language section, select your preferred language and then select Set as Preferred.
-
Select OK to save your changes.
To change the proofing language, in the Office authoring languages and proofing section, select Add a Language.
-
In new Outlook, on the View tab, selectÂ
 View settings. -
Select General > Language and Time.
-
Under Language, open the list and choose a different language.
-
Set or clear Rename default folders so their names match the specified language, and select Save. (The default folders are Inbox, Calendar, Sent Items, and so on.)