Mcafee Epolicy Orchestrator - How do I alter the schedule of a daily client AV update?

I am sure this is simple, but I did have a look and couldn't find anything. The property page of the particular task that updates the AV dat (or whatever) on client PCs doesn't contain any options to change the schedule.

I 'inherited' the setup from previous IT Managers, and the schedule is 9am and 9pm. Some of our users like to switch their PCs off when they leave, and so their PC is never on for any of the two update times. I therefore want to either - Change the overall schedule, Or - Alter it for the PCs in question.

Anyone know where I find this setting in Epolicy Orchestrator?