Android : App name doesn't change language after user changes it programmatically

I give my user the opportunity to change the app language. I use this:

public void languageToLoad(String language) {
    String lang = language;
    Locale locale = new Locale(lang);
    Locale.setDefault(locale);
    Configuration config = new Configuration();
    config.locale = locale;
    getBaseContext().getResources().updateConfiguration(config,
            getBaseContext().getResources().getDisplayMetrics());
}

for english: languageToLoad(en) or french: languageToLoad(fr)

But my problem is that the app name won't change.

strings.xml (en):

<string name="app_name">SoccerPro</string>

strings.xml (fr):

<string name="app_name">FootballPro</string>

Every string changes its value but not 'app_name'.

If the device language gets changed then it changes but not like my way. What am I doing wrong?