Customizing the Report Widget is very straightforward and easy. Please see the video for a brief discussion and example of customizing a Report Widget.
Please note, once a Report Widget has been changed, that "profile" is automatically saved for your Dashboard. There is no "Save" button on the page, rather it is done in the background, automatically when something changes. This means if you click to another page in software, logout/login and return to your Dashboard, it will be the same as when you left it.