States and variables

I have a project (attached) that has both states and variables that I'm struggling with.  This is a tab interaction where the user is free to visit any of the topics (tabs) at any time and in any order.  I have disabled the tabs until the user completes the topic before being set back to "normal" so they then can navigate to a different tab or topic.  I have also created a variable that displays a button called "summary" after all the topics have all been completed that takes the user to a summary and completed slide to exit the course.

Here are the problems I can't seem to figure out:

• The client wants the tabs to have a visited state (color change) so the user knows what they have and haven't visited but still wants the ability to go back to previously visited topics.  I have the states to go back to "normal" after the topic is finished so the user can go back to a topic...
• When a user has gone through all topics and the Summary button is displayed - if they don't take the opportunity to go to the summary slide and exit the course, the vicious cycle starts all over again and they have to visit all topics before seeing that summary button again!  How do I get it to stay once all topics are visited and they navigate to another topic?

Any help is TOTALLY appreciated!

Thanks,

Rachel