Instructions from the video:

Gable end walls can be constructed in 3 different ways to suit your construction method of balloon framing, framing a gable end wall, or using a gable end truss.

For our example model, select Insert>Roofs> Roof by Perimeter command to put a roof over the entire structure. Select a roof from the catalog and then left click in the middle of the model and the hip roof is formed.

Now left click to select 1 side of the roof overhang where a gable is required. Arrows appear on each separate roof surface. The arrows control, pitch, plate height, and style. Select the arrows on the sides that need to be made into gables. With both arrows green, right click, and select Properties.

In the Roof dialog box, select the Roof Shape button and change the roof shape to Gable. Click OK and the roof is now a gable roof running horizontally on the model.

By selecting the 3D Perspective view  3D camera, we can see the roof in 3D.

Select View>Framing>Display Framing to strip away the finish materials and see the framing. Currently the gable end wall is balloon framing up to meet the underside of the gable roof. That is an automatic setting with the exterior walls.

Select View>Framing>Display All But Framing to bring the materials back. Select a wall under a gable end, right click, and select Properties.

In the Walls dialog box, select the Top and Bottom tab. This tab deals with height and we can see it is set to Auto Extend. Meaning the wall will automatically extend up to meet the roof and change its shape to match the gable if need be. We will set the height of the wall to level instead. Give it a flush height of 8’-1 1/8” and click OK.

There is now a flat wall top and we can see the gap at the top of the wall and the gable. It is wide open. Let us now form a gable end wall in that area.

Select the 2D Plan icon to put the model back into a 2D view. Left click to select the roof overhang over the gable end. With one green arrow, right click and select Properties.

When a roof shape is converted to a gable, it gains a parameter “Display Gable”. Currently, it is set to None. Display gable is an option to fill in the triangular gable area of a wall. With it set to None, there is nothing there, we assume the wall beneath the gable is set to “Auto Extend” to balloon frame that area. Left click to select None, a drop-down list appears. There are three options: None, Surface or Wall. Set it to Surface. A surface material is used to fill in that area. No framing is added. This is an excellent option if you have a gable end truss and just need the finish materials shown and calculated.  The “Appearance Tab” lists a component “Gable End” and that is the material that will be shown in the gable end wall area. If alternatively, the Display Gable option is set to Wall, it will build a fully framed wall up in the gable end wall section. An additional parameter, Wall Type, appears to select a wall from the catalog to use for the gable end. Select a wall. Once selected, click OK. Click OK again to see the new gable end wall.

Select View>3D Cameras>3D Perspective.

The gable end wall is finished in the alternative material and we can see the finish. Selecting View>Framing>Display Framing, we can also see that it has been framed as a separate structure as well. Gable end walls can be ballooned framed, using a surface if a truss will be used or it can be a gable end wall. I hope that makes your work easier.