Layer keeps showing - only want it visible once

When an action occurs, it runs through all the triggers that are attached to that action. Thus, when the timeline ends on Check Match layer, all the "when timeline ends..." triggers ate executed, even the ones that are not related to the current action. That's why Match 1 correct shows up every time the timeline ends. To prevent that, you need to put something in the trigger to prevent it from showing more than once.This trigger will not show it if the variable has not changed to True:

Then you need a method to change the variable to true when the layer Match 1 Correct is shown. This one will do that:

By the way, I notice that the Check Match layer has only one trigger to show a correct match (Match 1).  I imagine you will add the others when it is working well. The attachment has only slide 2.10, so you can import it into your project.