After you create a wall opening endcap style, you need to assign it to the wall style where you want to use it when adding the following objects to the wall: doors, windows, openings, and door and window assemblies. 
When necessary, you can override the wall opening endcap style assigned in a wall style on an individual wall. 
-  Click 

. 
  
- Expand Architectural Objects. 
 
- Expand Wall Styles, and select the wall style to which you want to apply the opening endcap style to. 
 
- Click the Endcaps/Opening Endcaps tab. 
 
- For Opening Endcaps, select an opening endcap style to use for each of the opening objects that can interact with the wall. 
 
- You can also edit an existing opening endcap style here, or create a new one from wall endcap styles, if necessary. 
 
- Click OK.