It may because “Avantree CF3001” is just defaulting as your Playback/Output device.
1. Please connect headphones/speaker to the headphone jack on CF3001.
2. If you use your computer speakers or headphones plugged into your computer as audio output, please make the bellow settings:
On a PC, Right-click on the in the task bar à Select Playback devices or Sounds à Playback tab à Right click and DISABLE the “Avantree CF3001” à ENABLE your desired Playback device.
On Mac, Open System Preferences and double click the icon à Click Output button à Select your desired output device from the list.