You modify wall properties, on the Properties palette. To open the dialog, do one of the following:
Select a wall in the drawing area, and then select a different family type in the Type Selector at the top of the Properties palette.
The properties of a wall vary, depending on whether it is an interior or an exterior wall. In addition, when you modify type properties, all walls of that type are modified. When you modify instance properties, the properties of a single instance of a wall are modified.