how to override pusher config values?

I need to use different Pusher account for a specific part of my web app, so I tried to override the config using the following:

   public function send(Request $request)
    {
        $general_pusher = config('broadcasting.connections.pusher');
        $message = Message::create([
            'from' => auth()->id(),
            'to' => $request->contact_id,
            'text' => $request->text
        ]);
        \Config::set('broadcasting.connections.pusher', config('cfg.internal_chat_pusher'));
        logger(config('broadcasting.connections.pusher'));
        broadcast(new NewMessage($message));
        \Config::set('broadcasting.connections.pusher', config('cfg.internal_chat_pusher'));
        return response()->json($message);
    }

then, I tried to test using a random value for which Laravel should raise an error, but no error and the messages get sent and received, but using the original/old pusher config values.

as you can see I used the logger instruction which give me the following:

[2020-09-19 14:06:09] local.DEBUG: array (
  'driver' => 'pusher',
  'key' => '1',
  'secret' => '1',
  'app_id' => '1',
  'options' => 
  array (
    'cluster' => '1',
    'useTLS' => true,
  ),
)  

but, even though the logger command output the values that should give the error, I get no error, and messages get sent and received perfectly.

how to use different pusher account for a specific event?

Update:

I tried to edit the brodcasting.php as follow:

 'connections' => [

        'pusher' => [
            'driver' => 'pusher',
            'key' => env('PUSHER_APP_KEY'),
            'secret' => env('PUSHER_APP_SECRET'),
            'app_id' => env('PUSHER_APP_ID'),
            'options' => [
                'cluster' => env('PUSHER_APP_CLUSTER'),
                'useTLS' => true,
            ],
        ],

        'redis' => [
            'driver' => 'redis',
            'connection' => 'default',
        ],

        'log' => [
            'driver' => 'log',
        ],

        'null' => [
            'driver' => 'null',
        ],
        'internal_chat_pusher' => [
            'driver' => 'pusher',
            'key' => env('INTERNAL_CHAT_PUSHER_APP_KEY'),
            'secret' => env('INTERNAL_CHAT_PUSHER_APP_SECRET'),
            'app_id' => env('INTERNAL_CHAT_PUSHER_APP_ID'),
            'options' => [
                'cluster' => env('INTERNAL_CHAT_PUSHER_APP_CLUSTER', 'ap2'),
                'useTLS' => true,
            ]
            ],

    ],


];

then in the send function inside the controller:

 public function send(Request $request)
    {
        $message = Message::create([
            'from' => auth()->id(),
            'to' => $request->contact_id,
            'text' => $request->text
        ]);
        Broadcast::driver('internal_chat_pusher');
        broadcast(new NewMessage($message));
        return response()->json($message);
    }
}

but still, the messages are sent using the original/old account configs.

via Chebli Mohamed