To change the UI language of your account, navigate to Profile > My Account > Language and select your preferred language. The available options currently include English, Portuguese, Arabic, Spanish, German, Japanese, French, Russian, and Turkish.
Screenshot: https://monosnap.com/direct/tPAQkVNAUwqcJLyXfmQIfY8qimbJJL
How can I restrict a subaccount from changing their email? https://drive.google.com/file/d/1YfBVWzbqD2puPBLvTxj3EKwx_EjrvqT8/view?usp=drivesdk