When i am doing section access on attached QVW,first time it is asking credentials and working fine ,for second time Qvw it is opening directly with out showing the credentials.
This is by design: QlikView Desktop will remember the credentials you last entered and apply them without bothering you any further. It doesn't mean that your document security is broken
If you do not like this feature, you can disable it by opening Settings->User Preferences->General and disabling the checkbox called "Remember Login Credentials Until QlikView Exits" (top left series).
Untill you are closing the Application, credentials are with QV cache, so it won't prompt for credentials when ever your re-opening the same .Restart QV Desktop Application(QV.exe) then it will prompt for the credentials..
It is a default QV Property. If you don't want to avail it then disable Remember Credetials in UserPrefernces under Settings in Menu Bar.