To change the number of posts that appear on your Related Content app, you will need to go to the Shareaholic plugin App Manager.
From the App Manager, under the Related & Promoted Content section, click the Customize button of the area you would like to edit.
This will bring up an iFrame. In the section that reads Number of Posts, select from the list of choices then Save Settings. Currently, we allow up to 4 - 16 recommendations and/or Promoted Content ads.