Reporting Services Reports in Dynamics Gp

I wonder if anyone can help on this...reporting services comes with predefined reports as you know, what I am looking for is this, is there a way to modify the predefined reports?  For example, under financial there is a Cash Position Detail report.  I know that this is using the Financial Category of "Cash" which is in position 1 of the Category list to build the report.  Is there a way in which I can change the category that the report is looking at?

Any help or pointers would be very much appreciated.

Thanks, Tracy