Automatic disk optimization in Norton 360

I've just bought a new PC which has an SSD as its system disk and an HDD for data.  Norton 360 reports that disk optimization is automatic; however, as SSD performance drops if constant defrags are run, I should like to specify when and what disks to optimize/defrag. 

Can anyone tell me if it's possible to switch off the automatic optimization - if so, how ?

From Main UI,  Settings > Tasks Scheduling > Automatic Tasks Tab > uncheck Disk Optimization > Apply