setLocale() doesn't change the language set by browser

Hello everybody



I'm new to CI and to any framework and it's just awesome!  
I'm not used to write in forums as I'm usualy allways able to find a solution already posted somewhere so it's my first time in 20 years of IT. So I hope my english is ok as the rules say "proper english only" and I correctly explain my problem.



So to my problem:

I'm making a bilingual site french/german with CMS features so I use bilingual db's and the CI locale feature.



The language recognition of browsers works fine but I'm unable to change the language through



$this->request->setLocale($language);

or

setlocale(LC_ALL, $language);



when I control it with getLocale() I can see that setLocale() works but there is no change in the views...



in Config/App.php

public $defaultLocale = 'de';

public $negotiateLocale = true;

public $supportedLocales = ['de-CH','de-DE','de-AT','fr-CH','fr-FR','fr-CA','fr-BE','fr','de'];      ( tryed also ['de','fr'] )



my switchlanguage-button calls Language.php Controller with:

PHP Code:

<?php namespace App\Controllers;
use CodeIgniter\HTTP\IncomingRequest;

class Language extends BaseController
{
    public function setLanguage($language)
    {
        $session = \Config\Services::session();
        $session->set('language',$language);
        $this->request->setLocale($language);
        $session->set('locale',$this->request->getLocale());
        /*setlocale(LC_ALL, $language);*/
        return redirect()->back();
    }
} 


I'm using session('language') to select the right columns in the db's and the locale for all the titles, bottons, validation errors and more...




in BaseController.php I got:

PHP Code:

$session = \Config\Services::session();
if (session('language') == null) {
    $locale = $this->request->getLocale();
    $language = substr($locale, 0, 2);
    $session->set('language',$language);
    $session->set('locale',$locale); /*<-this only for debuging*/
} 


Can you see where I'm wrong? I can't find a solution. CI locale strictly follows the Browsers properties and I can't change it...
I'm sure it's something stupid


thank you