All browser windows will share the identity of this external app (e.g. Google,Facebook)
When you sign-out from this application you will be still signed-in in the external app (e.g. Google,Facebook)
If already signed-in the external app (e.g. Google,Facebook) you will not need credentials, you will be immediatly signed-in with that identity
If you log on to this app with external app (e.g. Google,Facebook),
and then log out and try to log in again with a different Facebook account (using the same browser),
you will be immediately logged in to the previous Facebook account you used. In order to use another account,
you need to navigate to Facebook and log out at Facebook.
The same rule applies to any other 3rd party authentication provider.
Alternatively, you can log in with another account by using a different browser.
