I don't exactly understand.
Are you using the Japanese version and you want it to display English? If so, you need the International/European version instead. The Japanese version only supports Japanese language. International version supports English, Italian, German, Spanish, and Japanese.
Or do you have the International/European version and want to change it (back) to English? On the menu, it's Display Mode (Alt+D), Language (G), then the second option English.
