When a report containing one or more parameters is added to a Dashboard existing report tile, those parameters are imported to the
Parameters menu. Click on the toolbar Parameters 

Each imported parameter is shown as an item in the menu. For example, the
Parameters menu below contains two parameters, one named MyParameter with a value Teleportation, and one named EmployeeID with the value Johnson.
Parameters menu with two parameters imported from reports on the canvas
If more than one report references the same parameter, it is grouped together into a Consolidated Parameter. This consolidation happens automatically. Clicking on any of the parameter items in the menu will open the Parameter Item Detail menu.
Parameter Item Detail for a single report
Parameter Item Detail for a consolidated parameter
The Parameter can be given a title by clicking on and entering it into the text field at the top of the menu. This title is used in the Parameters Pane of the Dashboard Viewer to more clearly identify it.
Providing a title for a Parameter in the Dashboard Designer
How the title in the Dashboard Viewer Parameters Pane appears
The name of the report or reports that imported this parameter are displayed under the title.
The parameter’s Name and Value are displayed, and the Value can be changed.
The corresponding tile names in the Affected Tiles section show which tiles are affected by the parameter. If two or more reports on the canvas have a parameter with the same name, those parameters are consolidated into a consolidated parameter. Click the Group All button to consolidate all of the reports with the common parameter
In the example below, the EmployeeID parameter appears on two reports, param-test1 and param-test2. In the Parameter Item Detail on the left, a Group All button allows consolidating all of the reports with the EmployeeID parameter. The resulting consolidated parameter is on the right.
Consolidated Parameters allow the Value to be changed for all of the reports simultaneously.
To break the consolidation, click the corresponding ungroup button.

The On Execute options work as follows:
Note
Changing the value of a parameter will require a Refresh of any tiles affected by that parameter.
To add a parameter to a Dashboard, it must be included in one of the Dashboard’s component reports.
To remove a parameter from a Dashboard, remove it from the reports on the Dashboard.