Returning from Incorrect layer to base layer

In a quiz, if students chose the incorrect answer, they are sent to the incorrect layer. Once students click on the continue/try again button they are returned to the base slide. 

1. When students return to the base slide, I don't want them to (re) hear the audio. When I use a true false variable with the audio, it turns my text to speech into an mp3, which then doesn't work when it's previewed or uploaded.  Or, it simply doesn't work. (see attached photo). 

2. In the quiz, I delay allowing students to click the submit button until the audio has been completed. When students return from the incorrect screen to the base slide, is there any way, (other than creating a new slide) to alter the slide so the submit button is available to use immediately? 

Thank you in advance!