I believe that the system keeps track of everywhere you go - for example, when you login to your Square Account, that's one session and one Device, as you navigate through your Account, each selection or area you go to is another session. I can login to the Community which starts a session and a Device and then I can go to my Square Account which starts another session and another Device - after checking things like my website and items, that opens more sessions. When I logout, I can have 20 plus sessions open. If I choose logout of all sessions, the system logs me out of my Account and also out of the Community - that's where the Device question comes into play. Understand that this is not an official Square response as I don't think you will find one but, it seems to be a logical thought. You would probably need to speak with Square Programmer for more specific details.
