Append a % sign in selected value that shows on slider handle

I forgot to add that this is in "mobile friendly" mode where the selected response shows in a handle.

I would also like to know the answer to this

Hi Annie and @mckelvey
You can achieve the same(to append "%") using the below code by adding below code into Qualtrics JS API:
Qualtrics.SurveyEngine.addOnload(function()
{
/*Place your JavaScript here to run when the page loads*/

});

Qualtrics.SurveyEngine.addOnReady(function()
{
/*Place your JavaScript here to run when the page is fully displayed*/
// Select the node that will be observed for mutations
const targetNode = document.getElementsByClassName("sliderToolTipBox")[0];
let observer = new MutationObserver(function() {
targetNode.innerHTML = Math.abs(targetNode.innerHTML)+"%";
observer.disconnect(); // turn observer off;
observer.observe(targetNode, {
 attributes: true,
 childList: true, // observe direct children
 subtree: true, // and lower descendants too
 characterDataOldValue: true // pass old data to callback
});// turn back on

});

// observe everything except attributes
observer.observe(targetNode, {
 attributes: true,
 childList: true, // observe direct children
 subtree: true, // and lower descendants too
 characterDataOldValue: true // pass old data to callback

});

});

Qualtrics.SurveyEngine.addOnUnload(function()
{
/*Place your JavaScript here to run when the page is unloaded*/

});

Hope it resolves your query😊!!!