Use the language selector to change the interface. The service remembers your last choice on that device. A supported language supplied in the URL takes priority, for example when opening a search-engine link. Without a saved or URL choice, the app tries the browser language and falls back to English. An advertisement or article without a published translation also falls back to its available English source; changing the interface does not create a translation of user text.
How do I change the interface language?
Choose a language from the menu and keep your preference.