Change Default User Language

[Jerami]

Hello, I'm trying to change the user default langauge. I have roundcube v1.4.7 installed.
I attempted to change the code in :
config --> defaults.inc.php
Line:
$config['language'] = 'fr_FR';

But after saving it and going back to the roundcube plugin on my website the default selected language is still English.

Any clue why that happens and how to fix it ?
Thanks in advance

[JohnDoh]

A user's language preference is stored when that user first logs in so changing the default after that will not change the setting for existing users. Users can change their own language setting from Settings > Preferences > User Interface > Language.

Also you should put any custom config options into config.inc.php, do not change defaults.inc.php. Changes in defaults.inc.php will not survive updates.