When you create a cross section, its center will appear at the center of the bounding box of the currently selected object or objects. If no objects are selected, the bounding box of all objects in the scene is used. Ideally, before creating a cross-section, you should select the object you want it applied to.

To create a cross-section:

1. Select the object or objects to which you want to apply the cross-section.
2. Select Appearance > Cross-Sections to open the Cross-Sections interface.
   
3. In the Cross-Sections interface, click Create.
4. Select Plane or Corner.