Twenty Fourteen Theme – only showing full posts instead of summaries

I’m setting up a site using the Twenty Fourteen theme – I’ve set the menus to link to categories, but when the page opens I want to only show the short summaries for the articles (so if users want to read the full article they’ll click on the link and open the page, rather than read it all on the ‘Category’ page). No matter what I do I can’t get it to only show the summaries.

This is the site: https://theclarionnews.wordpress.com/

I’m only using the Free online version of WP right now (there’s a possibility that might change in future but not right now).

Any help greatly appreciated.