BI web services - login info

I am trying to create a dashboard based on webi reports and using the bi web services connection.

How do I ensure the username and password is passed on from the user that is logged on to launchpad.

Currently I have hardcoded it and do not want do that.

There is no row level security or anything. The username and password are inputs in the web service connection type and trying to figure out how this can be passed on automatically from launchpad.