LibreOffice Impress - Insert sound on all slides

Hi everyone,
Can anyone tell me how to insert an audio file on all slides of a LibreOffice Impress presentation ? I can insert an audio file on one slide only and don’t find the way to make it continuing on the other slides too.

Thanks for help

I have version 6 and it still won’t play the music continuously for a series of slides. I follow the instructions carefully, and no luck. The audio is fine for the first slide, and then it quits on the mouse click. I use mp3 files. SO VERY FRUSTRATING! This is for a church presentation.