To change the default icon assigned to a taskbar pinned program, here are the steps you can follow without involving a 3rd party tool:
1. Right-click on an icon you would like to change, say Google Chrome, and right-click on the same program name from the jumplist, and choose Properties.
2. Click on the Change Icon… button.
3. Pick up a new icon showing in the list, let’s say the yellow Chrome.
4. Click OK twice to get out of the properties window.
Now you have successfully changed the icon for taskbar pinned Google Chrome but you won’t be able to see the change right away. You can either wait for the next cycle of IconCache rebuild which I don’t know how often it takes place, or you can follow the steps below to refresh the IconCache manually.
1. Go to the local appdata folder by opening the following from Search box in Start menu
2. Delete or remove the file IconCache.db file, which will be rebuilt from the next boot.
3. Either reboot your computer or restart Explorer.exe process to refresh the new icon you just set up. To restart the explorer.exe process, simply run the following two commands in the Dos Prompt window:
taskkill /f /im explorer.exe
4. Now let’s see what the new icon looks like from the taskbar.
The change you made through this process is only valid as long as it’s pinned on the taskbar. If you unpin it and re-pin the program back you will need to re-do the process again to make the change. So think twice when you unpin any program from the taskbar.