Layer and Trigger Issue

Hello, 

I am working on a project where I have created buttons on the base layer that when clicked on bring you to a layer within. After a learner has seen each layer, I have created a "close" button to bring them back to the base layer to click on the next button. All of that is working. My issue is creating the correct trigger or variable that will disable the next button on the base layer until every layer has been seen and then make the next button "normal" to be useable after everything has been viewed. 

Please help!