How to choose the default locale for Filament? editing "locale" in config/app.php dindn't work

The default language of Filament now is in English, I want to change it to Arabic so I changed the value of locale in config/app.php but the language in Filament is still English! The locale outside Filament is "ar" which is expected, but in Filament routes the locale is "en". I have the translation files of Filament Arabic. I use bezhanSalleh/filament-language-switch and I change the language using it without any problem.