If you haven't already installed the app:

Download the latest version of the soundcore app (version 4.0.1) from App Store/Google Play. Within the app, add a device and select "soundcore C50i" to connect.

If you have already installed the app:

1. Uninstall the previous version of the app.

2. Go to App Store/Google Play on your phone and update the app to version 4.0.1 or higher.

3. After updating, open the app, tap Add Device, and select "soundcore C50i" to connect.

If you encounter any other issues or your issue has not been resolved, please contact us for further assistance.