Bose QuietComfort Headphones audio is delayed or out of sync

The checks in more detail

Start by finding out where the delay appears: if it is only in one app, that app's player is not compensating, and trying another player or updating it may fix it. If it appears everywhere, look at the codec and the connection. The QuietComfort Headphones support the common codecs, and Android phones that support the aptX family offer a lower-delay option, which you can see in Developer options under the Bluetooth audio codec on many phones, though the phone and the headphones both have to support it.

On a computer, a Bluetooth adapter from the same era may be the weak link, so try a different adapter or the computer's built-in one. Keep the headphones close to the source and away from busy 2.4 GHz traffic, since interference causes retransmissions that add delay. Disconnect the second device if you use two at once, because connecting to two devices at once can add overhead. Update the headphones' firmware in the Bose Music app, which has fixed connection and delay issues in the past, and update the phone or computer.

For gaming and video editing where timing matters, use the audio cable that comes with the headphones, since a wired connection has no wireless delay. Some video apps have an audio sync or audio delay setting that lets you shift the sound; use it if available. A TV connected over Bluetooth will usually be worse than a phone, so for TV use a wired connection or a transmitter that supports a low-delay codec. If the delay suddenly appears where it was not before, restart both devices and forget and pair again. If everything is slow on every device, contact Bose support with the serial number.