Why are the audience fields grayed out or disabled?
If you have activated DocRead against a SharePoint document library and you are unable to assign audiences to a document because they are disabled then this article explains how to resolve the issue.
The reason the audience fields are disabled is because you aren’t in the group as specified in the ‘DocRead Publishers’ Group. To solve this follow these steps :
1. Navigate the ‘DocRead Site Settings’ screen (in the site that contains your document library).
2. Locate the ‘DocRead Publishers’ Group and make a note of the group that is selected. (You many also change the group to one that you are a member of).
3. Navigate to the SharePoint Groups page and add yourself as a member.
4. Now edit the document properties and the audience fields should be enabled.