Each graphical Dashboard component comes with a legend that explains the conventions used in the component. Unfortunately there isn't much you can do to change those legends except to move them around to different areas of the component.
The first thing you'll want to do is identify the component that you feel needs a legend relocation. By default, all the legends reside on the right-side of the component like the one you see in the following screenshot:
1. Click the Dashboard icon on the navigation bar to access the Dashboard view.
2. Select the Dashboard you want to modify from the Dashboard drop-down list and then click the Edit button on the Dashboard tool bar. The Dashboard designer opens.
3. Right-click on the component that you'd like to change and select Component Configuration from the contextual menu; the Component Configuration wizard appears.
4. Click Change Legend from the Component Tasks area of the Component Configuration...