Disable a button, once used. Change States or Variables?

I have probably boofed this up pretty good. The attached sample has 3 scenario choices on the main screen. I disabled the next button and want it to enable upon the user selecting all 3. I also want a selected scenario to show checked and become disabled once the learner selects it (i.e. I don't want the learner to keep accessing the same scenario. Each one only once and then move on)

I have tried changing states and/or setting up variables but I am not having success. Any help would be appreciated