Problem with the sound on Slide Layers

I have a story that finish with a slide with the base layer and 5 layers (each one have sound), all of them have selected "pause timeline of the base layer" but when I test in the following way:

The first time, when I select de slide with slide layers, and play the base layer, I select any of the slide layers and all plays ok, stops the sound in the base layer.

BUT if I click on the previous button, and I start to play the previous slide, and then I click the next button, to the last slide with slide layers, it starts with the base layer, and if I select any of the layers, the sound of the base layer DOESN'T STOPS,  so if I select all the 5 layers, the sound of the 6 slides plays at the same time.

Any suggestions to correct this situation??

thanks a lot