When you place the mouse over a Widget that can be configuredm a small italicized "i" will appear on the Widget.  Click it, the Widget will flip and preferences specific to that Widget will appear.  These examples show the "i" on the bottom right and preferences of the Weather and Clock Widgets.

 

 

 

Save the Changes
When you have finished making changes, click "Done" to save the changes.  The Widget will flip back to it's original position and will be updated to display any changes you made to the settings.