WordPress Custom Taxonomy Terms Custom Order in Dashboard & Admin Panel

I have WordPress taxonomy custom registered and in Admin panel its terms are being shown in Alphabetic order. I want to change it in custom order as in order they were added. So in Dashboard and Add New Post and Edit Post screen, the taxonomy widget should show terms in the order I select and not just alphabatically.

I see there is a plugin for this, however i wanted to accomplish this using custom code.

I have tried the parameter “sort” from this page: register_taxonomy codex. But still no success so far.

Following is my code:

add_action( 'init', 'register_taxonomy_page_assignments' );
function register_taxonomy_page_assignments() {
$labels = array(
'name' => _x( 'Page Assignments', 'passign' ),
'singular_name' => _x( 'Page Assignment', 'passign' )
);
$args = array(
'labels' => $labels,
'public' => true,
'show_in_nav_menus' => true,
'show_ui' => true,
'show_tagcloud' => true,
'show_admin_column' => true,
'hierarchical' => true,
'rewrite' => array( 'slug' => 'page','with_front' => false),
'query_var' => true
);
register_taxonomy( 'passign', array('post','ad_listing'), $args );
}