Using Variables to Change Button States

You are correct in saying that variables hold their values throughout the project. But you are relying on initiating a trigger when a variable is changed. Variables announce a change only to the slide on which they change. It does make sense. Only the current slide is functioning, and you don’t want every “when variable changes” trigger in the whole project firing each time a variable changes.

So if a variable changes on one slide, then you return to a different slide, it will not know that the variable has changed. The best way to handle that is to write your triggers to initiate “when  the slide timeline starts if the variable equals True” (or False, as the case may be). Whether you have return to slide to set to initial or saved condition, the timeline restarts, so that trigger will execute.