Barbella, sorry to here this, have you tried changing the Audio settings in system, then system again. Then check the setting level at the bottom left corner is set to advanced, now check
Video output..check this
Use a fullscreen window rather than true fullscreen is on
Vertical blank sync Change to Alway enabled
Now go to Audio output.. Check this
Number of channels matchs your set up ie stereo =2.0
Enable passthrough is set off
Now go back and go to video (in system) then playback
Turn off Adjust display refresh rate it match video and sync playback to display is not highlighted
Now go to Acceleration and Decoding method is set to Hardware accelerated and highlight Libstagefright and Mediacodec.
Try this please and see if it works, if not at least we tried, good luck and many thanks Dave