Change Image State On Exit of Another Slide (Storyline 360)

You can use T/F variables to track what slides the user has visited, and use that info to adjust the images on your menu page.

• You'll need a variable for each slide (or topic) in the menu.
• Have the default value be False.
• Change the appropriate variable to True when the timeline starts on the associated slide they need to view.
• For each image on the menu page, use a trigger that changes the image's state to the alternate color when the timeline starts--with the condition that the associated variable is True. 
  • Note: I suggest that you put those triggers on an invisible (aka blank) layer that "Resets to initial state" when revisiting. There's more info about that trick in this post: https://community.articulate.com/discussions/articulate-storyline/tip-the-incredible-power-of-invisible-layers 

Here's more info about conditions and variables: 

• https://community.articulate.com/series/articulate-storyline-360/articles/storyline-360-working-with-triggers#conditions
• https://community.articulate.com/series/articulate-storyline-360/articles/articulate-storyline-360-user-guide-how-to-work-with-variables