Perspective windows show the view from a camera object. Camera objects exist in the scene just like curves, surfaces, or lights, although they are usually not visible.
You can create new cameras, and change which camera’s view a particular perspective window displays.
Multiple cameras are most useful when rendering, to have various cameras set up at fixed positions to render with, while maintaining a perspective window camera to use while working on the model.
Pick the camera and change its object name in the Information window.
In the perspective window title bar, press the camera menu icon and choose a camera from the pop-up menu.