Change Your Account's Primary Language
Your account's primary language is the language you will enter new content in and the default display language for any new users that you add.
To change your account's primary language, click and view your Language settings.
You'll first need to make sure that the language you want to use has been added to your account. You can do this by selecting the language from the Language dropdown and clicking +Language.
After you've added the language to your account, you can select it from the Primary Account Language dropdown.
Note: Switching the account's language will not affect existing users and content; it will only affect users and content that are added after the change.