For more details, please check the Customizing the HTML5 Report Viewer help section.
Note there is an option to customize report parameters' editors
, where the settings are per editor, not groups of editors.
Also you can use the HTML5 Report Viewer's events
exposed as of Telerik Reporting Q2 2014 SP1 version 220.127.116.114 to know when to update the viewer's parameters area.
Another approach is to use a custom UI for report parameters, and pass the user selection as in the How To: Pass values to report parameters
I hope the above information is helpful.
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.