Steps to change the number of recent posts in WordPress
Blog Dashboard ->
Appearance >
Widgets >
Recent Posts >
Edit > [Set desired number of posts]
Tried this as well – didn’t quite work:
Dashboard > Settings > Reading > Blog pages show at most
References
1. Increase the number of recent posts shown on page:
http://wordpress.org/support/topic/increase-the-of-recent-posts-shown-on-page