When you make changes to the theme file, those changes will be applied to users who aren't logged in, and new users registered after that. It does not update existing users.

There is a database command that you can run to reset existing users to a certain stylesheet.

<pre>UPDATE w3t_Users
SET U_StyleSheet = 'somestylehere'
</pre>

Maybe someone will post a database command that will update the number of posts displayed per page.