Yt_swishsh_chan.user.js

// ==UserScript==
// @name         Yt swishsh chan
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://www.youtube.com/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=youtube.com
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    function getElementByXpath(path) {
        return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
    }


    const headdiv = getElementByXpath('/html/body/ytd-app/div[1]/div/ytd-masthead/div[4]/div[1]');
    const swChan = getElementByXpath('/html/body/ytd-app/ytd-popup-container/tp-yt-iron-dropdown/div/ytd-multi-page-menu-renderer/div[4]/ytd-multi-page-menu-renderer/div[3]/div[1]/ytd-account-section-list-renderer[4]/div[2]/ytd-account-item-section-renderer/div[2]/ytd-account-item-renderer/tp-yt-paper-icon-item');

    const pmjp = document.createElement('div');
    pmjp.innerHTML = `<span style="color: white; font-size: 18px; cursor: pointer;">S</span>`;
    pmjp.addEventListener('click', () => {
        swChan.click();
    });
    headdiv.appendChild(pmjp);

})();