This Knowledgebase article describes why the Configure Monitoring console should not be run on the passive server.
Neverfail does not recommend running the Configure Monitoring console on the passive server with versions of Neverfail Heartbeat prior to V4.3. This is because the configuration file is replicated from the active to the passive server. Any changes made on the passive server will not be propagated to the active server, and will be over written by the active server.
Changes to settings in the Configure Monitoring console should only be made on the active server.
From Neverfail Heartbeat V4.3 onwards, a warning message will be displayed if you attempt to open the Application Module GUI on the passive server, or attempt to save changes from an open GUI instance after the host machine has been switched from the active role to the passive role.
Neverfail Heartbeat prior to V4.3