I've used the following workflow many times to change the state of menu buttons after sections are completed and it works great:
Add a Completed state to each menu button.
For each of the sections, create True/False variables, initially false.
On the last page of each section set its corresponding variable to true.
Then on the menu slide add slide triggers for each of the buttons setting them to the Completed state when the timeline starts if the corresponding variable was true.
However, when the menu slide has audio, I don't want to use the when timeline starts event to kick off a state change or other triggers because the audio will keep replaying every time the user revisits the menu. Any suggestions on how to still use True/False variables to trigger state changes without making the timeline restart every time the user revisits a slide?