The function "Global unsubscription" allows to unsubscribe a contact from all the lists at the same time. You can activate this option in your "Profil", in the section "Settings" on the left. Don't forget to save your choice!
Every contact already unsunbscribe in at least one list, will unsubscribe during an update from all the lists in your account.
For exemple, if a contact, unsubscribed in the "List A" and active in the "List B", is re-uploaded, it will be automatically unsubscribed from the "List B".
If contact already usubscribed is upload in a new list, it will be automatically usubscribed.