If the sound automatically becomes smaller when playing videos and music on your mobile phone, we recommend the following:

1. Make sure you are using the video/music player that comes with your mobile phone.

2. Play the video or music on your computer and check whether the file is normal.

3. Use the camera or recorder that comes with your phone to record an audio or video and check whether it is normal.

4. Uninstall recently installed software.

5. If the above operations fail to play normally, please back up important data and restore the phone to factory settings.