Cams are tied to an account. Account is tied to email/password combo. If you want to be able to view any/all cams from one login, tie all cams to one account. Then you can group your cams by location for organization if you wish.
If you create seperate accounts for each location, you’ll have to log out of one account and sign into the other account in order to view different locations.
Note that if you plan on sharing access to any of your cams by giving out your email/password and they are all under one account, those you share with will have access to all of your cams.