I've downloaded and installed Mozilla Firefox, Portable Edition, Version 78.0.1 for Windows, in English.
I've tried to change its taskbar icon following the steps described at https://portableapps.com/node/61043, but it doesn't seems to work for this version.
I've also tried a lot of different path, sizes, and format variants without any success:
Does anybody know how to change Firefox taskbar icon in recent versions?
I've been trying to work this out myself for ages, and finally figured out a way to do it
Following this guide:
Use the portable/zip version of Resource Hacker obviously.
In Resource Hacker, open up the FirefoxPortable\App\Firefox64\firefox.exe file. Then right click "Icon" on the list on the left, and click "Replace icon."
Under "Icon to replace" select the "32512" entry, click "open file with new icon" and then choose the new icon you want. Click "replace" then close and hit the save button in the main window.
Now when you launch Firefox Portable it will display the taskbar icon that you choose.
Note that this will get overwritten every time Firefox Portable is updated so it's not a great solution but it's the only one that works for me