In the attached file, I've set the characters' state to visited after you click on each one. However, I am able to click on characters in the visited state and they toggle to normal state.
I don't want the user to be able to click the character in the visited state at all.
Disabled is the only visible state that doesn't allow the user to click an object with triggers.
On the slide, a character doesn't toggle back to Normal when it is clicked. It toggles back to Normal when the previous character is re-clicked. That's because the first 5 characters all have a trigger that changes the next character to Normal.
One way to prevent that is to add a condition to those triggers so a character is only changed to Normal if it is in the Disabled state as shown in the image below. That's been done for all the characters in the attached file.
Obviously, that still allows folks to re-click any character. I think they should be able to do that, because they might want to review the info. (Which is why I also think the layer associated with the last character should have a Back button.)
However, if there is a good reason to prevent re-clicking, you could put a 100%-transparent shape over each character. Have the Initial state = Hidden, and use a trigger to change it to Normal when the character = Visited.