Setting the Active Project
The active project is the project that will be built when you use the Build or Rebuild All commands. It is also one of the determining factors in the building of dependent projects. For more information about dependent projects, see Creating, Including or Removing Subprojects.
To set the active project
On the Project menu, click Set Active Project and choose from the submenu of project names.
-or-
On the Build toolbar, choose a project from the Select Active Project drop-down list. (To view the Build toolbar, right-click an empty part of the menu bar and check Build.)