There are 2 options to solve this;

Use any of the supported services for file storage i.e Amazon S3, Dropbox, FTP, Rackspace

Follow the steps below;
Create a folder in /public folder named /storage
Move all folders from /storage/app/public/ to the folder you created /public/storage/
Open file config/filesystems.php and change the values as shown;

 'local'     => [
            'driver' => 'local',
            'root'   => public_path('storage'),
        ],

        'public'    => [
            'driver'     => 'local',
            'root'       => public_path('storage'),
            'url'        => env('APP_URL') . '/storage',
            'visibility' => 'public',
        ],

Now open file .env and change or create the values as shown below;

    AVATAR_DIR=avatars
    SIGNATURE_DIR=signatures
    LOGOS_DIR=logos
    MEDIA_DIR=media