This is the index.php of the current version of this theme
http://themes.svn.wordpress.org/preference-lite/1.6.5/index.php
in that file, notice the loop here
<?php while ( have_posts() ) : the_post(); ?>
<?php get_template_part( 'content', get_post_format() ); ?>
<?php endwhile; ?>
that get_template_part() will look for the content-{postformat}.php and use it when it matches the post, and defaults to just content.php
Here are the content-{postformat}.php files in that theme
content-aside.php
content-image.php
content-none.php
content-page.php
content-quote.php
content-single.php
content-status.php
content.php
You have to go over them and change the_content(), if found, to the_excerpt(), if you don’t use post format, just change the content.php one.
Also, all the modifications must be done in child theme only.
http://codex.wordpress.org/Child_Themes
Hi hope4autism…I wanted to follow up with Paulapxp’s reply and to see if you were able to get the excerpts in place?