When using Post UI tabs plugin its a bit tricky to set the default tab but not that hard,
you need to create your own JavaScript file and put it in your themes folder
, lets say you call it custom_script.js
inside it add:
jQuery(document).ready(function($){
$("#tabs-1").tabs("select", - 2);
});
this is assuming that you don't have more then one set of tabs on that post/page.
then add this snippet to your themes functions.php file:
add_action('wp_enqueue_scripts','my_tabs_script');
function my_tabs_script(){
if (is_page('SLUG')){
wp_register_script( 'my_tabs', get_bloginfo('template_directory') . '/custom_script.js',array('jquery','post-ui-tabs'), '1.0' ,true);
wp_enqueue_script( 'my_tabs' );
}
}
this will only load your newly created script on a page with the slug of SLUG you can use it on posts by changing is_page('SLUG')
to is_single(''SLUG_OR_ID)