BenQ M73 Series Operation Manual page 24

3. Tap the Search button to detect available projectors.
4. Tap the preferred projector and your mobile device will connect to the projector.
5. A preferred device prompt will display. Tap Yes if you want to set the projector as
the default projector. If the projector is set as the default projector, the next time
you launch QCast your computer will search for the projector and automatically
connect to it if it is available through the network.
24 Projecting via QCast (for mobile devices)