Going back to previous question/block without allowing changing previous response

Try: input.prop("disabled",true);
You can disable all the elements with jQuery. You can use the developer tools in the browser to help pinpoint the input if you need help with that.

Thank pogi! I tried add something like
Qualtrics.SurveyEngine.addOnReady(function()
{
input.prop("disabled",true);
});
and
Qualtrics.SurveyEngine.addOnReady(function()
{
jQuery("#"+this.questionId).prop('disabled',true);
});

But they did not prevent me from moving the slider. Am I doing it wrong?

This https://www.qualtrics.com/community/discussion/2385/prevent-changing-the-handle-in-a-slider-question solves the problem perfectly!

Be careful with this solution, the slider can still be changed using the keyboard after disabling pointer events.

Hi ahmedA , thanks so much for the heads-up! I never knew it. Do you have an alternative solution by which we can disable the slider entirely?

Nope. I haven't been able to figure out the slider yet. Perhaps in a few days I may have an answer.

Could you just hide it and display the numerical value on return or display a second slider set to the appropriate selection but will not record on the original question?