Strange that no one has made it yet, here's a script for this:
// ==UserScript==
// @name Bitcointalk Highlight My Name in Merit
// @version 1.0
// @grant none
// @include https://bitcointalk.org/index.php?topic=*
// @run-at document-end
// ==/UserScript==
;[...document.querySelectorAll(".td_headerandpost")].forEach(post => {
let myName = document.querySelector("#hellomember b").textContent
let allMerits = [...post.querySelectorAll(".smalltext i > a")]
let myMerit = allMerits.find(e => e.textContent === myName)
if (myMerit) {
myMerit.style["font-weight"] = 1000
if (allMerits.indexOf(myMerit) !== 0) {
let myScore = myMerit.nextSibling
post.querySelector(".smalltext i").removeChild(myMerit)
post.querySelector(".smalltext i").removeChild(myScore)
allMerits[0].before(myScore)
myScore.before(myMerit)
}
}
})
Screenshot:

Also check my related userscript that sums all merits of a post ->
https://bitcointalk.org/index.php?topic=5148488.msg52264117#msg52264117