You can change the way you view your data in a widget by transforming it to a different type of visualization.
Click on the transform icon in the widget title bar. A drop down menu shows the various types you can convert the widget into. Choose the one that suits your requirement and the widget transforms.
Some of the widget types require a specific or certain minimum number of dimensions or metrics. If the current data doesn't match that setting, a message is displayed on the widget. Once you make the necessary changes, the visualization would be visible.