See forum thread http://jasperforge.org/plugins/espforum/view.php?group_id=112&forumid=10...
The current functionality For Save Param Values is at a report level so all users who have access to the report can see the Saved Param values that other users have saved.
This should be at a per user basis. Where JS is in a Multi-tenancy environment users share the same reports but shouldn't be able to see the Saved Param Values of other users.
Thanks for catching it! The defect is already logged in internal tracker.