Summary Text on Home Page

Currently my home page is showing the entire article for each of my posts.

I would like it to just show the headline and like 100 character summary, and then if the reader wants to read the most they click on it.

I’ve gone to Settings > Reading > and set “For each article in a feed, show” to “Summary” and nothing has changed, its still showing the whole article on the home page.

How do I fix this? My blog posts are fairly long so this makes looking for posts really difficult.

Note: It also happens on the category pages. I would like those pages to only show headline and preview as well.