Make Post Editor Select Number of Columns To 1 By Default

Ok, so this is how I did it. This hook into the admin head, find the screen options part and set the default checked radio button to 1, which mean full screen.

Just found the answer from here and give it a little modification:

        add_action( 'admin_head', 'wpse1152474_post_editor_columns');

        function wpse1152474_post_editor_columns() {
        global $pagenow, $typenow;
        if ($pagenow == 'edit.php' || $pagenow == 'post.php' 
           || $pagenow == 'post-new.php'
           && $typenow=='your_targeted_post_type') {
            add_screen_option(
                'layout_columns',
                array(
                    'max'     => 2,
                    'default' => 1
                )
            );
          }
        }