Change Button State to Visited when another scene has been viewed

Hello all,

I've done some digging in the topics and have seen similar questions to mine.  However, I have not been able to get it to work quite that way I would like.  I believe it may have to do with utilizing variables, but I'm quite new to exploring them.

Attached is a sample of what I am trying to accomplish.  We would like to have 4 buttons that link  to other scenes that contain content.  Once the users have finished viewing the scene, we want to button to switch states to visited. 

I've tried playing with the variables a bit, I've created custom visited state button, but can't seem to wrap my head around how it works.  Does anyone have any ideas on how to accomplish this? 

Thank you

(We use SL3 at the moment).