You’ll need to understand Template Hierarchy and determine what template is displaying those posts then change that template to display more than one post.
If following heirarchy is true for my template hierarchy, I should change the category.php file because category-{slug}.php and category-{id}.php don’t exist. Am I on the right track? If so, what exactly needs to be changed on the template?
Category Templates:
1. category-{slug}.php – If the category’s slug were news, WordPress would look for category-news.php
2. category-{id}.php – If the category’s ID were 6, WordPress would look for category-6.php
3. category.php
4. archive.php
5. index.php
Yes you are on the right track…
Typically the number of posts displayed would be controlled by either the template using the argument like ‘posts_per_page’ when doing query_posts OR the Blog pages show at most setting Administration > Settings > Reading.
I checked the Blog pages show at most setting. I have it set to show one post per page, because I only want the latest post to display on the front page. I did an experiment and tested to see if setting it to 10 posts per page would change the way the categories are displayed. It did change it to showing 10 excerpts. However, I changed it back because I really don’t want more than one post to show on the front page.
I couldn’t find ‘posts_per_page’ but I could have looking in the wrong places.
Please paste all the code from the theme template file (probably category.php) that is displaying those posts into a pastebin such as wordpress.pastebin.com, and report the link back here. Maybe someone can spot your problem. Thanks.