Select your preferred layout. In essence you are defining how many columns of widgets you want to see on your overview. The minimum is one column, the maximum is three. Note that changing the layout after the overview screen is already configured is still possible. If you reduce the number of columns the system will simply move the widgets from the removed column to the new far right column. Meaning that widgets located in the third column would move to the second column if you opted for a new layout with two columns.