[Only registered and activated users can see links. ]

Based on no information you have left us - as said and discussed so many times - common problem. Browse Forum. Read.
Spoiler: sys part

navigation_audio_stream=3
;0-VOICE_CALL
;1-SYSTEM
;2-RING
;3-MUSIC
;4-ALARM
;5-NOTIFICATION
;6-BLUETOOTH
;8-DTMF

This command is placed in the appropriate section, but we do not know which one because you did not leave which OS your device has.
Usually under: [android]

Add this line, or if exists. try to change values.
Or read unit manual and try to do better setup.