How to customize posts per page?

The website is http://news.abnxcess.com

In each category (Home, World, ShowBiz..) if I click on the “Video” section title, it will lead to a listing of all videos http://news.abnxcess.com/category/home/videos/.

The problem is, there’s only 10 videos listed and the pagination for it is on the right side where people won’t be able to see. How can I make the listing shows 30 videos per page plus a pagination on the bottom?

I don’t want to change the Reading Setting in the Dashboard because it will change the other listing in others category (example for Biz category) http://news.abnxcess.com/category/biz/?ismore=1.

I already tried $query = new WP_Query( ‘posts_per_page=30&cat=videos’ );