I found this forum by having the same problem, however with a different program. I found a solution for my situation and figured I would post for anyone having a similar problem. I had several options grayed out when modifying a scheduled task through Task Scheduler on Windows 8.1. On the General tab I changed Configure For from its default of "Windows Server 2003, Windows XP, or Windows 2000" to my version of Windows being Windows 8.1. When I went back through the other tabs the options that were previously grayed out are now usable. Hope this helps anyone else having this problem and comes across this old forum.