What you want to ask is why Toyota Rongfang plays music with Bluetooth and turns on the navigation, so the sound changes. The reason why Toyota Rongfang plays music with Bluetooth and turns on navigation music is the problem of vehicle system setting, Bluetooth connection and music file format.

1. On-board system settings: In some on-board systems, when the navigation sound prompts, the on-board system will automatically reduce the music volume to ensure that the navigation sound can be clearly transmitted. Incorrect setting of the on-board system will lead to the mixing of navigation prompts and music sounds, which will lead to the change of music sound. You can adjust the settings of the in-vehicle system to ensure that each sound can be transmitted independently.

2. bluetooth connection problem: the bluetooth connection between the mobile phone and the in-vehicle system is unstable, which will cause the music to change sound. In this case, you can try to reconnect Bluetooth or use other connection methods, such as USB connection or AUX connection.

3. music file format problem: the music file format is not compatible with the vehicle-mounted system, which will cause the music to change its sound. You can try to convert the music file to a format supported by the in-vehicle system, or use other music files.