Change language

Where can I change the language of my account to English?

I can't find the option to change language, and when I created the account it never asked me what language I wish to use.
I want to set it to English because currently it is half Portuguese and half English, and it's annoying. Additionally, the "inbox" is incorrectly translated to "caixa a enviar" which means "sending box". And I can't figure out which is the "sent items" folder. I mean, it's all mistranslated! It's annoying and confusing...

Thank you!