All Accounts are mixed

Hi,

I am a PM, so I set up all my team's account.
My account is gjguo.csie (at) gmail.com
I used my own computer to register all accounts I need
When I logined in any new account, the site went to my account only, not the new one.
It didn't work even I tryed another browser.
What can I do to break the wrong linkages?
Team A2：
TeamA2.No1@gmail.com

Thanks.