Low audio | Bose QuietComfort Ultra Earbuds (2nd Gen)

Be sure you're wearing the earbuds correctly.

A proper fit is important for comfort and sound quality. If the earbuds are not worn properly or positioned incorrectly, audio and microphone performance may be affected. See Wearing and adjusting your earbuds for more details.

Reset your earbuds.

Just like restarting your phone can fix small issues, resetting your earbuds can help resolve minor problems.

Place the earbuds in the case - the light inside the case should illuminate.
Close the case and connect the charging case to power.
Once the light on the front of the case illuminates, press and hold the button on the back of the case until the front light turns off.
Remove the earbuds from the case.

Here's a video tutorial:

Try a different app.

If the issue only occurs with a particular app, it is likely related to the app or app settings.

Try playing different types of media.

Different media types might produce different quality sound. For example, Podcasts, music stored locally on your phone, MP3s, streaming music services (Spotify, Pandora), videos on your device or stored in the cloud, etc. can all vary in quality. Try different media to determine if the issue is specific to certain media.