Trigger based on variable not working

Hi

Sorry if this is a dumb question, but it's not something I've tried before. I'm wondering if it's just not possible, but in theory I feel like it should work! 

I've created a project with a menu screen. Each option branches the learner to a new scene. When they complete that scene and return to the menu screen, I want them to see a 'completed' state on that menu option. To do this, I've

• Created a true/ false variable defaulting to false
• Added a 'completed' state to the menu option
• Added a trigger to a shape on the last screen of the branching scene which they must click to return to the menu screen. This trigger is to change the variable to 'True'
• Added a trigger to the menu screen to change the state of the menu option to complete when the value of the variable is true
• Set the menu screen to 'auto decide' revisited state

It just doesn't work- the state of the menu option doesn't change. Does anyone have any ideas? Fell free to tell me if I'm completely barking up the wrong tree! :) Thank you!