Clearing Or Refreshing Parameters??

Question

Hi,

Ive created a Crystal Report Viewer. I have a drop down list that allows the users to select a report and then the parameters display accordingly.

However, when I go to select a different report, the report changes but the previous parameters remain on the page...

I was wondering whether someone could help me. Im assuming I need to either delete or refresh these parameters. If this is the case, could you show me how to do this?

Thanking you in advance