NW, Portal, switching between users

So..
When working in Portal, you want to switch between users ,and when you try to do so, it appears that IE is logging- in with previous credentials.
This appeared not to be Portal issue or something.
All you need to do in this case is following:

GO TO IE settings;
'Advanced' tab;
Scroll down to 'Security' menu;
Tick 'Empty Temporary IE files when browser is closed'

SAVE
Restart

That's about it.

Now every time IE is closed, your NW session is getting closed as well and with following run, you will have to enter credentials of new user.