My Thunderbird Icon on the taskbar has changed and I can't get back to the original icon. Attached is a picture of the task bar where the white rectangle with the "2" in red, is now the Thunderbird shortcut. I've tried a right click on it, then right click on thunderbird, then properties, then change icon, but it doesn't change it. I've looked online for other advice and am about to tear my hair out. I would appreciate any clue, and thank anyone in advance for advice.