OK, you have a basic roundabout. How do you edit the various widths, radii, etc. to match your specific project needs?
1. Select the item which needs to be adjusted.
2. Click the manipulator.
3. Type a new value or drag the point to a new location.
Edits to the approach lanes
Deflection area edits
Or, if you prefer, all the edits are available in element information
1. Select the roundabout
2. Element information
3. The related graphics will highlight as you navigate the property pane allowing you to edit in the element information dialog.