With the Implicit Action policy, WhatsUp Gold automatically assigns actions to all devices in your database. There is no way to opt out of the Implicit Action policy, so any action in that policy will be used by all devices. The Implicit Action Policy is not used for active monitors, just devices.
The Implicit Action policy is configured and can be edited through the Action Policies dialog. If at any time during the normal operation of WhatsUp Gold you notice that actions are firing and you cannot find the action associated to the down device or monitor, remember to check the Implicit Action Policy too.