Front-end (User Interface) default language

[Toofan Karvanian]

Hi,

We have add one more language (French), we need to make French as default language for Front-end (User Interface) and keep English as default for Back-end (Admin panel), But we can't find how to do that !!! when we select FR as Default language in Basic settings or in Languages section, the Admin panel and the Front-end are in Frensh.

Thank you