Menu buttons and change state variables

Hi all.

I feel like I am missing something obvious, but I can't see it.  

1) I want menu buttons to show "completed state" when relevant topic is complete

2) Have topic complete variable changing to "true" when timeline on last slide in topic begins.

3)Topic complete variables are working for "pause audio".

4) Can't get them to work for changing the state of buttons.

See image.  

Thanks!