早上好，我有几个页面，在应用程序栏中有一个按钮，可以很好地更改语言，当我更改语言时，我关闭应用程序，然后重新打开应用程序，一切都很好。当我更改语言时，我通过单击图像在页面之间导航，它也很好。
我的问题是，当我改变语言，我点击左箭头在顶部的Flutter应用程序（appbar）的语言更改是不适用于在前一页！你能帮我请。谢谢。

import 'package:flutter/material.dart';
import 'package:firstapps/language/langue.dart';
import 'package:provider/provider.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:firstapps/pages/auther/Index_history.dart';
import 'package:firstapps/pages/Visites.dart';
import 'package:firstapps/pages/Carte.dart';
import 'package:firstapps/pages/mv.dart';
import 'package:firstapps/pages/lmhb.dart';
import 'package:firstapps/pages/hbd.dart';

class Accueil extends StatefulWidget {
  const Accueil({Key? key}) : super(key: key);

  @override
  _Accueil createState() => _Accueil();
}

class _Accueil extends State<Accueil> {
  late SharedPreferences _prefs;
  String _langue = '';

  @override
  void initState() {
    super.initState();
    SharedPreferences.getInstance().then((prefs) {
      setState(() {
        _prefs = prefs;
        _langue = _prefs.getString('langue') ?? 'fr';
      });
    });
  }

  void _changerLangue(String nouvelleLangue) async {
    setState(() {
      _langue = nouvelleLangue;
    });
    await _prefs.setString('langue', nouvelleLangue);
  }

  Widget _buildGridTile(String title, String imageAsset, Widget page) {
    return GridTile(
      child: InkWell(
        onTap: () {
          Navigator.of(context).push(MaterialPageRoute(builder: (context) => page));
        },
      child: ClipRRect(
      borderRadius: BorderRadius.circular(10.0),
          child: Container(
            decoration: BoxDecoration(
              image: DecorationImage(
                image: AssetImage(imageAsset),
                fit: BoxFit.cover,
                colorFilter: ColorFilter.mode(Colors.black.withOpacity(0.6), BlendMode.darken), // Assombrit l'image avec un opacité de 0.5
              ),
            ),
                      child: Center(
              child: Text(
                title,
                style: TextStyle(
                  color: Colors.white,
                  fontSize: 24,
                  fontFamily: 'poppinslight',
                ),
                textAlign: TextAlign.center,
              ),
            ),
          ),
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<SharedPreferences>(
      future: SharedPreferences.getInstance(),
      builder: (BuildContext context, AsyncSnapshot<SharedPreferences> snapshot) {
        if (snapshot.hasData) {
          final prefs = snapshot.data!;
          final _language = Language();
          final _langue = prefs.getString('langue') ?? 'fr';

          _language.setLanguage(_langue);

          return ChangeNotifierProvider.value(
            value: _language,
            child: Scaffold(
              appBar: AppBar(
                title: Text(_language.transchoixcat()),
                actions: <Widget>[
                  DropdownButton<String>(
                    value: _langue,
                    onChanged: (String? nouvelleLangue) {
                      if (nouvelleLangue != null) {
                        _changerLangue(nouvelleLangue);
                        _language.setLanguage(nouvelleLangue);
                      }
                    },
                    items: <String>['fr', 'ar'].map<DropdownMenuItem<String>>((String value) {
                      return DropdownMenuItem<String>(
                        value: value,
                        child: Row(
                          children: <Widget>[
                            Image.asset(
                              'assets/images/flag-${value}.png', // chemin de l'image correspondante
                              height: 24,
                              width: 24,
                            ),
                            SizedBox(width: 10,),
                            Text(value),
                          ],
                        ),
                      );
                    }).toList(),
                  ),
                ],
              ),
              body: Center(
                child: GridView.count(
                  crossAxisCount: 2, // nombre de colonnes
                  mainAxisSpacing: 16.0, // espacement vertical entre les images
                  crossAxisSpacing: 16.0, // espacement horizontal entre les images
                  padding: EdgeInsets.all(16.0),
                  children: [
                    _buildGridTile(_language.transhisttoir(), 'assets/images/histoire.jpg', Index_history()),
                    _buildGridTile(_language.transvisit(), 'assets/images/visites.jpg', Visites()),
                    _buildGridTile(_language.transcart(), 'assets/images/carte.jpg', Carte()),
                    _buildGridTile(_language.transvide(), 'assets/images/mv.jpg', mv()),
                    _buildGridTile(_language.transmise(), 'assets/images/lmhb.jpg', lmhb()),
                    _buildGridTile(_language.transapro(), 'assets/images/hbd.jpg', hbd()),
                  ],
                ),
              ),
            ),
          );
        } else {
          return Container();
        }
      },
    );
  }
}```

when i change the language it works great my only problem is with the back button which is in the appbar of flutter, when i change the language and i go back the language is not applied but when i click on the images to lavigate the language is well applied.