Problems with multiple layers and audio

I'm using Storyline 1. I've had it for a while, but am just starting to develop more complicated courses with it, so pardon in advance if this is a bit of a newbie question.

I've got multiple audio-related questions, but this one may be the key to the others. The page I'm working with contains five layers, including the base layer. The base layer contains four buttons, each of which navigates to another layer. All layers have audio files and each button on the base layer has a visited state.

I've added a trigger to the buttons to shut off the audio on the base layer when they're clicked. Likewise, there are triggers on the Close buttons on the other layers to shut off the audio there.

The problem is, if you click a button on the base layer before that layer's audio finishes playing, then you return to the base layer, the audio picks up right where it left off. I want it to stay shut off when a user returns to the base layer to click another button.

Is there a way to make that happen?

The actual file I'm working with contains proprietary information, so I've set up a similar interaction in the attached file.

Thanks,

- Jennifer