how to disable a variable interaction after one use

Hi Maria & Joseph,

Thank you SO much for your help and advice - it worked! I'm not really sure why I used a numeric variable that adds value each time the user visits the summary slides (your assumption @Maria was correct) and so it didn't matter how the slide's properties were set when revisiting (resume saved state / reset to initial state) the variable kept changing hence my issue. I guess I just assumed the option for the variable to be true or false would also keep changing upon revisiting but thankfully it doesn't, as you've rightly advised :) 

Thanks so much again, our customer is now going to be very happy this issue has been fixed with their module,

Best wishes and huge gratitude, 

Edward