All widgets display cahed data so there may be slight delay in display. However, your prmium theme appears to have it's own unique Recent Posts widget. Read-access to the premium themes forum is now open to all users so you can search to see if your question has been previously asked and answered there. The premium theme forums are at http://premium-themes.forums.wordpress.com/ with separate sections for each theme.
If you are not successful when searching there is a link for the specific Premium Theme support forum for your theme under Appearance -> Themes in your blog’s Dashboard, but do note that the premium theme must be active and you must be signed in as the user who purchased it in order to see it and post to it.
All support documentation for WordPress.com bloggers is at this link http://en.support.wordpress.com The results produced by the searchbox there are from both the support docs and from forum threads.
On the bottom of your Admin page you will find a link to the learn wordpress.com tutorial prepared by Staff. http://learn.wordpress.com
Best wishes with your blog.