There are 2 methods for selecting stair components for editing. In project mode, you can select individual stair components (Stair, Run, Landing, or Support). For more options, such as the ability to select a chain of connected runs, you must first select to edit the stair to enter stair assembly edit mode.
To select a stair component in project mode (outside of stair assembly edit mode)
Information in the status bar can help you identify when you have highlighted the correct component.
To select a stair component in stair assembly edit mode
You can select any of the following: