Why does the state of a caption change automatically when slide's timeline ends

I have created a slide in which I want the user to click on all of the little orange speech bubbles. I have created the variable called ModifyaPerson2visited which starts as False and only changes to True once all of the speech bubbles were visited.

If the user clicks on 'Next' and the variable is False, it won't go to the next slide and this works.

My problem is that I want the 'Rounded Rectangular Caption 1' to appear only when the user clicks the 'Next' button and the variable is False. As you can see in the attachment, I have made the Caption 1's initial state invisible but as soon as the slide's timeline ends, the Caption 1's state changes to the state I called NotHidden even if the user doesn't click on 'Next'.

Your help would be greatly appreciated.

Sarah