Sequential Buttons 1-6, How to set up TRIGGERS?

I saved your slide as Original.

Judging from the original slide, I think you want the ovals to show a selected state when clicked, but only change to the Visited state when they are clicked in order.

Check my version of Brainteaser2 slide.

First, if you select all the ovals and right click them, you can make them a Button Set. That gives them the built-in superpower that changes the last clicked one to Selected state, and all the others to Normal. No triggers necessary.

Then if you want to change them to Visited state, but put a condition on it, you do need a trigger for that, but now the built-in superpower is a problem. If you leave it to its natural state, it will always change when the oval is clicked, and you can't use a condition. If you create a trigger to change it if the condition is true, you risk creating a conflict between your trigger, and the built-in superpower. When that happens, you can get results that are sometimes interesting, but never useful.

So you have to create a new state that doesn't have a built-in name, so you can create your own trigger without conflicts. I used the name "Investigated", and I created it by copying the Visited state, naming it, and deleting the Visited state.

I only did this for ovals 1, 2, and 3, but you can see how it works.

The ovals change to selected when clicked, and change to Investigated it the previous oval has already been visited. (4, 5, and 6 retain their old actions, as I didn't change them. The built-in superpowers work with the triggers to handle everything.