Each time you publish an Answerset from a project, a version of the answerset is created and previous versions are retained. To expose all versions, click on the show all versions options (highlighted in red) under the version number as shown in the image.
To select a specific version of the Answerset, click the green "Select" button in the lefthand column. Versions of Answersets are exposed whether you are directly viewing the library or viewing the library via a Project "select dataset" conversation. The green "select" button is only visible during the "select dataset" conversation.
If you choose the "Select" button next to the parent Answerset, this will select the latest version available.