The Hijacked Audio
macOS is designed to manage audio routing intelligently, especially when dealing with the Apple ecosystem. However, its Bluetooth behavior can be frustratingly aggressive. If you have previously paired a Bluetooth speaker to your Mac, the operating system will often automatically reconnect to it the moment the speaker is turned on within range, and immediately route all system audio through it. If you turned on your living room speaker to listen to music from your phone, having your Mac suddenly hijack the connection and blast an email notification sound through the living room is incredibly annoying.
Severing the Auto-Connect
To retain absolute manual control over your audio outputs and stop macOS from automatically connecting to specific Bluetooth speakers, you must explicitly forget the device profile in the system settings.
Unlike iOS, macOS does not offer a granular “auto-join” toggle for individual Bluetooth devices; you must completely remove the pairing. Click the Apple logo in the extreme top-left corner of your screen and select System Settings. In the left-hand sidebar, click on Bluetooth. On the right side, you will see a list of “My Devices.” Locate the specific Bluetooth speaker that keeps hijacking your audio. Hover your mouse over the speaker’s name, and click the small ‘i’ (info) icon that appears next to it. In the popup window, click the button labelled Forget This Device, and confirm your choice. Your Mac will no longer seek out or automatically connect to that speaker. The next time you actually want to use it with your Mac, you will have to manually pair it again.