Show newer YouTube comments (com.vsubhash.js.show-youtube-comments-newer) is a User Script for YouTube that will display newer comments first instead of the default moderated "Top Comments". This script can be installed in Firfox browsers using the Greasemonkey add-on.

com.vsubhash.js.show-youtube-comments-newer

// ==UserScript==
// @name        Show newer YouTube comments
// @namespace   com.vsubhash.js.show-youtube-comments-newer
// @description Automatically changes YouTube comments filter off
// @include     https://www.youtube.com/watch*
// @exclude     %exclude%
// @version     2018
// @grant       none
// ==/UserScript==

 
document.addEventListener("DOMContentLoaded", startItDelayed, false);
  
function startItDelayed() {
  window.setTimeout(switchCommentsList, 10*1000);
}
 
function switchCommentsList() { 
  console.log("Showing newer comments");
  var arButtons = document.getElementsByTagName("button");
  console.log(arButtons.length);
  
  var bFound = false;
  for (var i = 0; i < arButtons.length; i++) {
    //console.log(arButtons[i].textContent);
    if (arButtons[i].textContent.trim() == "Top comments") {
      arButtons[i].click();
      bFound = true;
      break;
    }
  }
  if (bFound) {
    //console.log("Menu found--------------");
    var arButtons = document.getElementsByTagName("button");
    console.log(arButtons.length);
    for (var i = 0; i < arButtons.length; i++) {
      //console.log(arButtons[i].textContent);
      if (arButtons[i].textContent.trim() == "Newest first") {
        arButtons[i].click();
        bFound = true;
        break;
      }
    }
  }
  
  
}