The Acknowledgement of Content (AOC) Items related list from the AOC page is not displaying columns based on the Content_Acknowledgement_vod layouts related list.
AOC opens the Content_Acknowledgement_View_vod Visualforce (VF) page rather than a standard SalesForce.com (SFDC )page. The Visual Force (VF) page AOC Items section is based on the AOC Item page layout rather than the related list of the AOC.
Configure the page layout of AOC Item to display the desired fields on the AOC page.
CRM Help Documentation: Acknowledgement of Content