public function actionChangePassword()
 {
     $model = new \backend\models\User(['scenario' => 'admin-change-password']);
     if ($model->load(Yii::$app->request->post()) && $model->validate()) {
         $user = User::findOne(Yii::$app->user->identity->id);
         $user->setPassword($model->password);
         $user->generateAuthKey();
         if ($user->save()) {
             Yii::$app->getSession()->setFlash('success', Yii::t('app', 'New password was saved.'));
         }
         return $this->redirect(['change-password']);
     }
     return $this->render('changePassword', ['model' => $model]);
 }