Have never liked the bright orange Firefox icon, but suddenly firefox is not letting me change it to the older one I like much better

Have never liked the bright orange Firefox icon, it's too dominating on my desktop, I LOVE the older brownish firefox icon, it's just right. So every time you come out with a Firefox update I get out "Resource Hacker" and change the icon to the older one, pictured below. I mentioned this before, asking if you could just give that option, and didn't receive a response. You come out with so many updates, it's a hassle changing the icon every time, but I'm willing to pay the price to escape the distracting bright orange icon, but now suddenly Firefox won't let me alter the icon in the exe. Was wondering if you'd have any suggestions. Have used Firefox exclusively for decades. Thank you very much.