By default Joomla will automatically locked these build-in module like "language switcher" module so admin unable to uninstalled it from backend.

If you would like to use this language switcher module, you can install this from backend > extension > module > click NEW > select Language Switcher > setup and published it

Hope this will help.

Thanks Arlex

Maybe a misunderstanding ...

I don't want to grant my USERS to switch from a language to another.

I want to change the language 'English' of my site by default (all menus, fields, etc.) to 'French'.
My users are Frenchs and they read only French :-)

Are they the same steps that you describe above?

Thanks in advance
Henri

You're welcome Henri.

Try take a look of my attached screenshot below, if you set default French language from this section, is it still render English word when the user view on your homepage?

yes as you can see in the 2 screenshots

Hi Henri,

You would have to install French in EasySocial language section as well.

If you are not able to download it on your test site(http://take.ms/M04Vn), then you would have to manually copy those French language files from your production site.

Hi Ray,

Should I copy only these 3 files ?

Done and it works!

Hey Henri,

I am really sorry for the delay of this reply as it is a weekend for us here. Thanks for updating us on this and glad that your issues are resolved now