To select the audio output device on a Macintosh® running OS X 10.4.6 or a later version, follow these steps:
Click the Apple® menu in the top left-hand corner of the screen
In the Apple® menu, click "System Preferences..."
Click the "Sound" icon
Click the "output" tab and select the Bluetooth® device from the list of available options
Click the "Red" button to close the control panel
Play audio from the computer (iTunes® etc.) to initialise the change