Windows is a weird ecosystem that has different types of apps, from legacy/Win32 to UWP/Modern apps. As a result, some apps allow us to change the icon of the apps pinned to the taskbar and some don't. To fix this problem, I've created a method that works regardless of what kind of app we want to pin to the taskbar which I've detailed in my HOW TO USE CUSTOM ICONS IN THE TASKBAR GUIDE. There are a few steps that involve a third-party app used to change the AppID of a custom shortcut, but if you follow along closely, you'll see that it works. I even have an example in the guide to make things easier. So now you can fully enjoy any custom icons on your taskbar but I highly recommend you to give my Retroism Icons Pack a spin: Have fun!