User's Acrobat 11 signatures have disappeared when they try to use them.

User's Acrobat signatures have disappeared from settings. When they click on the pen shortcut or go to sign/work with certificates/sign with certificate signature options don't appear. Gets a different screen that wants to direct to where signature is. When I go to edit/preferences/signatures/creation & appearance "More" signatures are all there but they aren't showing up when signing