Follow up question:

We must use firefox for work, and we have some required addons/extensions that are required to be installed. Also, we cannot use firefox newer than 56, because the extensions are not compatible with the latest Firefox, so the preferences/options have to be set to never update. One of the 2 extensions is a great kiosk addon "mkiosk", which we really need in order to control a user's behavior on firefox. This kiosk extension is crucial. Other crucial settings include 'never checking for updates' etc, as stated before. I was working on a machine I was using as a setup builder, I have firefox 56 all configured the way I need it, and I am signed in. Then on a different machine, also running firefox 56, I signed in. Only one of the extensions installed [not the kiosk addon] and none of the preferences. The bookmarks were the only thing to sync. And to answer the foreseeable question: I have Bookmarks, Add-ons and Preferences checked as synced elements. And -not- Open Tabs, History or Logins. ================= Follow up question: ================= If we can get the sync to work properly - is there a way to select one device as the 'admin'[main] device so that only one specific device's extensions and preferences will push to all other devices when they get signed in?