How to change the appearance of a disabled quiz button?

I use this code since you never know the id. You can also use this (slightly modified) to get a reference to a SmartShape button on a master slide.

This code changes the cursor, prevents rollover states and changes opacity.

var elems = document.getElementsByClassName("cp-accessibility");

    for(var i = 0; i < elems.length; i++)

    {    

     if (elems.getElementsByTagName("p")[0].innerHTML.indexOf("Submit")!== -1)

     {

      var getSubmit = document.getElementById(elems.getElementsByTagName("p")[0].parentNode.parentNode.id);

      var getSubmitCanvas = document.getElementById(elems.getElementsByTagName("p")[0].parentNode.parentNode.id+"c");

      getSubmit.style.cursor = "default";

      getSubmit.style.pointerEvents = "none";

      getSubmitCanvas.style.opacity = 0.5;

      getSubmitCanvas.style.pointerEvents = "none";

     }    

    }

Understand now what you mean, Since user cannot change any answer after leaving the question slide, I do not allow backward movement in quizzes, it has not much sense,

Down state has a typical meaning in all applications that use buttons: appears when the button is down, Buttons on quiz slides are embedded, which means they cannot be addressed in an action to change to another state. The pause of the quiz slide is linked to that Submit button, and its two-step process, After the second step the actions On Success  or, after exhausting the attempts on Question level, the Last attempt action are done, You could use those actions to add a note on the slide. You can add a shape button, but the embedded objects are always on top of custom objects, covering the Submit button is not possible. That is the reason why JS will be the only way.

Not true, sorry. The quiz buttons cannot be shape buttons. However both

transparent and image type of buttons are allowed. You can change fill and

border for transparent buttons, you can design image buttons. No need for

JS at all.