Truly Minimal theme – how to appear only summary of article on Home page?

Hi!
How can I set the theme Truly Minimal to show me only a summary of the article in the Home stream?
I mention that I recently installed it also on a second site – test.inimafericita.ro – (which I use to test different changes that I intend to do on the main site), and on the test site it shows only a summary of the articles on the Home page, as I would like to have on my original site (inimafericita.ro)
I do not have different settings for these sites. Why is this happening and how can I change it? I am opened even to a manual setting for each article, because I like the theme very much.
Thank you!