To edit the roof base, first click on the roof to open the properties panel on the left.

Click Edit Shape in the lefthand panel. Once in the Sketcher mode, sketch in the changes you intend to make to the shape, and click on Apply to save changes.

To edit the roof slope, first click on the slab to open the properties panel on the left.

Click Edit Shape in the lefthand panel.

Once in the Sketcher mode, select that boundary edge of the roof of whose adjacent face you wish to change the slope. Go to the Roof Edge Setting menu in the lefthand panel and type in any value from 1 to 90 degrees in the Slope Angle (deg) field (0 as a value is not applicable). Click apply to save changes.

Note: 90 degrees cannot be applied for all sides of the roof.