Profile: ivanJ

add_action( 'pre_get_posts', 'my_change_sort_order'); 
    function my_change_sort_order($query){
        if (($query->is_main_query()) && (is_tax('product_cat'))){
         //If you wanted it for the archive of a custom post type use: is_post_type_archive( $post_type )
           //Set the order ASC or DESC
           $query->set( 'order', 'DESC' );
           //Set the orderby
           $query->set( 'orderby', 'title' );
        } 
    };