I'd like to change the default disk thresholds in SCOM2012 to fit in better with my environment, but I'm not sure where to set this up.

I have the following enabled monitors:

Windows Server 2008\Entity Health\Availability\Windows 2008 Logical Disk Free Space Monitor

So, I assume I need to create my custom overrides in the above monitor?

Why are the following monitors disabled?

* Windows Server 2008\Entity Health\Availability\Logical Disk Free Space

* Windows Server 2008\Entity Health\Availability\Windows 2008 Logical Disk Free Space Monitor\Windows Server 2008 Logical Disk - Free Space Rollup Monitor\Windows 2008 Logical Disk Free Space (%) Low

* Windows Server 2008\Entity Health\Availability\Windows 2008 Logical Disk Free Space Monitor\Windows Server 2008 Logical Disk - Free Space Rollup Monitor\Windows 2008 Logical Disk Free Space (MB) Low

By default, Windows 2008 Logical Disk Free Space Monitor is enabled and you should modify its threshold.
Windows 2008 Logical Disk Free Space Monitor: Enabled by default, Alert is generated if both % of free disk space and MB of free disk space are below the threshold
Logical Disk Free Space: Disabled by default, this is old version of Windows 2008 Logical Disk Free Space Monitor and Alert is generated if both % of free disk space and MB of free disk space are below the threshold
Windows 2008 Logical Disk Free Space (%) Low: disabled by default, Alert is generated if % of free disk space is below the threshold
Windows 2008 Logical Disk Free Space (MB) Low: disabled by default, Alert is generated if MB of free disk space is below the threshold

Situation:
Just want alert generate if both  % free disk space and MB free disk space are below the threshold  ==> enable Windows 2008 Logical Disk Free Space Monitor only
Just want alert generated if  % of free disk space is below the threshold ==> enable  Windows 2008 Logical Disk Free Space (%) Low monitor only
Just want alert generated if MB of free disk space is below the threshold ==> enable Windows 2008 Logical Disk Free Space (MB) Low monitor only

Roger