Language Picker is not available to all users
The Language Picker is not available to all users.
ServiceNow is designed to display the language picker only to users who have a specific role. For those who do not have a specified role, the system will display the language that is in the user profile. If a language does not exist in the user profile, the system will display the default language.
For users who do not have a specific role, the administrator can either add a role to the user account or select a default language. For additional information, refer to Translate an Instance in the ServiceNow product documentation.