This is the setting on the VNM model (-> Alarm Management), so once you "set" it, it will take the change. So, no need to restart the SpectroServer.
It is an Application Model called "AlarmMgmt" and the setting is changing attributes on it. You can search for this model in Locater -> All Application Models -> filter on "AlarmMgmt". In the attributes tab of this model you can filter on this changed attributes like "age". Changed on the VNM model and you can see this attributes changing with it.
The "AlarmMgmt" model will be synced with an Online Backup and with it your changes to the secondary SpectroServer.