Language Settings per User
To define the default system language for a particular user:
Navigate to System > User management > Users in the main menu.
For the necessary user, hover over the More Options menu to the right and click to start editing the configuration.
Select System Configuration > General Setup > Language Settings in the menu to the left.
For faster navigation between the configuration menu sections, use Quick Search.
Clear the Use Organization check box and select the default language for the UI elements displayed in the back-office.
Click Save Settings.