You must unlock the Configuration panel first to perform any changes.
Before proceeding, you must stop the Channel by deactivating the checkbox. Stopping the channel will also stop the Just Out Primary engine output, unless there is a Redundant engine available.
Configuration panel - provides more basic settings. The Channel needs to be stopped before a setting can be changed.
Just Control MultiViewer Settings Tab - and the Channel tab in the Library of the dedicated user interface, provides additional settings and the settings there can be changed while the channel is running.