transition mouse click song plays over song

[Dawn]

My first slide has several songs to play one after another and it is set up
so on the last song it is to stop playing and not go onto the next slide
however a mouse click. However, if we want to start onto the next slide
before we get to the last song, you click and it appears to play several of
the songs on top of each other and you need to click a second time for it to
go the second slide. I go to custom animation and nothing appears there that
doesn't look right. I appreciate any help. I have searched all over for
answers.