Comment 2 for bug 1276072

Dragging some French option to the top in Language Support should be sufficient. Please make sure that it stays on top before closing Language Support. (You may need a couple of attempts.)

There is normally no reason to edit ~/.pam_environment manually, and /etc/environment should not be used at all for setting language/locales. However, since you did edit ~/.pam_environment, it might explain why it doesn't work as expected. Can you please post the contents of your ~/.pam_environment file.