Last night, I just changed the theme of my blog at http://patokfilipino.wordpress.com to Twenty Eleven. I tried to customize the number of posts per page to only show 5 but it doesn’t seem to work. It continues to show other older posts as I scroll down.
If you place one empty text widget in any footer area on your blog and refresh that Reading page, then you will find you will have the option to disable infinite scroll, and regain control over how many posts display on the front page of your blog.
Go to Appearance->Widgets and you will see the footer area. Put a blank text widget in it.