How work some icons?

That should be possible. First open your new icon in the editor and locate iexplore.exe (by default in C:\Program Files\Internet Explorer) and BACK IT UP.

Then click "Customize application icon" from "Icon" menu and browse to iexplore.exe, select it and the select the old icon that you want to replace. Click OK - the icon on your desktop may not change immediately, because it may be cached by Windows, so you may need to restart or rebuild icon cache using TweakUI power toy.