Use of apply_filter in plugin/widget class

I'm having difficulties to find out what I'm doing wrong in my use of apply_filter() in a widget class.

Here's some samples of my code:

class Byad_CountDown_Widget extends WP_Widget {
  function __construct() {
    parent::__construct(
      'byadcd_widget',  // Base ID of widget
      __('BYAD Countdown Widget', 'byad-countdown'), // Widget name will appear in UI
      // Widget description & class
      array( 
        'description' => __( 'Widget for displaying a countdown (Years (opt.), Days, Hours, Minutes, Seconds)', 'byad-countdown' ), 
        'classname' => 'byad-countdown',
      ) 
    );

  }

  public function widget( $args, $instance ) {

    $title = '<span class="byad-title">' . $instance['title'] . '</span><div class="arrow-container"><div class="arrow-up gray"></div><div class="arrow-up white"></div></div>';
    $title = apply_filters( 'byad_title', $title );//Try to add the possibility of changing the widget title via add_filter()

    // before and after widget arguments are defined by themes
    echo $args['before_widget'];

    // some code to implement some vars

    if ( is_active_widget( false, false, $this->id_base, true ) ) {
      wp_enqueue_script( 'byad-countdown', plugins_url( 'js/byad-countdown.js' , __FILE__ ), array('jquery'), '1.0', true );

      $params = apply_filters('byad_jsdata', array(
        'byadClass' => 'countdown-display',
        'byadImg' => '/byad-countdown/images/skull.png',
        'byadAlt' => '.',
        'year' => __('Years', 'byad-countdown'),
        'month' => __('Months', 'byad-countdown'),
        'day' => __('Days', 'byad-countdown'),
        'hour' => __('Hours', 'byad-countdown'),
        'min' => __('Minutes', 'byad-countdown'),
        'sec' => __('Seconds', 'byad-countdown'),
      ) ); //Try to modify the array passed to the JS file

      wp_localize_script( 'byad-countdown', 'jbydCD_Data', $params );
    }

    echo '<div class="countdown-display"  data-root="' . plugins_url() . '"></div>';

    if ( ! empty( $title ) ) {
      echo $args['before_title'] . $title . $args['after_title'];
    }

    echo $args['after_widget'];
  }

  // Widget Backend 
  public function form( $instance ) {
    if ( isset( $instance[ 'title' ] ) ) {
      $title = $instance[ 'title' ];
    }
    else {
      $title = __( 'My Default title', 'byad-countdown' );
    }
    //here goes Widget admin form
  }

  // Updating widget replacing old instances with new
  public function update( $new_instance, $old_instance ) {
    $instance = array();
    $instance['title'] = ( ! empty( $new_instance['title'] ) ) ? strip_tags( $new_instance['title'] ) : '';
    return $instance;
  }
} // Class Byad_Countdown_Widget ends here


// Register and load the widget
function byad_load_widget() {
    register_widget( 'Byad_Countdown_Widget' );
}
add_action( 'widgets_init', 'byad_load_widget' );

As you can see I've made twice the use of apply_filter to be able to hook into the variable passed to my widget: byad_title and byad_jsdata.

But when in my theme function.php file I do the following:

function my_title($title){
  $title = 'you know what?';
  return $title;
}
add_filter('byad_title','my_title');

Nothing happen, even if I change the priority of the add_filter function

I'm looking for any advice, because after running the net and different answers and possibilities, I haven't had any success to make it work.