Midhun there are usually 2 ways by which userid and password authentication is done with Webservice either passing it at http header level which is done simply by configuring user authentication at channel level and other way is by passing at soap header level which can be done by addsoapheaderbean/custom soap envelope by java or xslt or by wsse in module level.
I would suggest you to try the same password at module level which you have already.