All components. Applies the feature to all components in the model every time the feature regenerates. If you add new components to the model that are intersected by the feature, these new components are also regenerated to include the feature.
Selected components. Applies the feature to the components you select. If you add new components to the model that you want the feature to affect, you need to use Edit Feature to edit the feature, select those components, and to add them to the list of selected components. If you do not add the new components to the list of selected components, they remain intact.
Auto-select. (Available if you click Selected components). Automatically selects all components intersected by the feature. Auto-select is faster than All components because when you make changes to the feature, only the components on the initial list are regenerated (instead of all components in the model). If you click Selected components and clear Auto-select, you must select the components in the graphics area you want to include.
Components to Affect
(Available
if you clear Auto-select). Select
the components to affect in the graphics area.
You set the feature scope for a feature in
a 
.