The color and thickness of a household boundary can be modified from the Pen Menu.
To create a household, select the Household Tool from the Tool Pad. Then drag the mouse around a circuit, enclosing a collection of figures who live together.
To modify a household, drop the mouse on its boundary, then drag it along the corrected path, making sure to release the mouse where the correction rejoins the boundary. If you don't get it right the first time, undo the change, and try again!