Currently you need to close the browser to change user details or purposely fail security before it let's you log on to a different account.
This can become frustrating for multi account users like myself (I have 3 sperate accounts) as whilst working I can have many web pages loaded and it requires me to close everything to log in as a different user.
I would like to see a simple link to change the account you wish to log in as at the login page when it asks for random characters of my password.