if( ! function_exists( 'videotube_footer_2_cols_sidebars' ) ){
    function videotube_footer_2_cols_sidebars() {
        unregister_sidebar( 'mars-footer-sidebar' );
        register_sidebar( $args = array(
                'name'          => __( 'Footer Sidebar', 'mars' ),
                'id'            => 'mars-footer-sidebar',
                'description'   => __('Display the Widget on Footer.','mars'),
                'before_widget' => '<div class="col-sm-6 widget %2$s">',
                'after_widget'  => '</div>',
                'before_title'  => '<h4 class="footer-widget-title">',
                'after_title'   => '</h4>'
            )
        );
    }
    add_action('widgets_init', 'videotube_footer_2_cols_sidebars', 100 );
}