Checking properties or Remote Control Host (right-click on Systray), the option "On abnormal disconnection" can't be changed:
How the values of Abnormal Disconnection option can be modified?
Client Automation - 14.x
This setting is managed by a policy under: DSM -> Remote Control -> Host -> General -> Abnormal disconnection action
As a way to keep track on changes made in the Configuration Policies, it's always recommended to create a new policy instead of changing the Default Computer Policy. Once the new policy is created, this can be applied to single computer or a group.