Sometimes, the solution suggested above doesn't work.
In these rare cases, try this solution:
What you need to do for the audio to restart when showing a layer again is to first stop that audio. If the audio isn't stopped, it will only resume when the layer is shown again.
The revisit option in the layer property only works if you move to another slide and then go back to the slide. The layer will then either reset to its initial state or resume its saved state upon revisiting the slide.
What you can do to restart the audio each time the layer is shown is to add a trigger to stop the media on that layer when the timeline starts. See this screenshot of the trigger in the attachment for reference
You just need to add that trigger on all the layers.