If you'd like to change the icon of an application (exe file) you can do it with IcoFX.
IcoFX can only handle uncompressed 32-bit files. If you try to edit a compressed exe file the behavior is unpredictable.
It is not recommended to edit exe or dll files. The file can be corrupted after the editing. Use this feature at your own risk. It is a better practice to create a shortcut to the exe file and change the icon of the shortcut. This way the exe remains unchanged.
To change the icon of an application follow these steps:
1. Start IcoFX
2. Open the Icon Resource Editor using the "Tools/Icon Resource Editor..." menu item.
3. Open the exe file using the "Open" toolbar button.
4. Select the main icon of the application and then press the "Change" toolbar button. In the appearing dialog select a new icon for the application. The thumbnail of the icon will change.
Change the icon of an application
5. To save the file press the "Save" toolbar button.
For more information about the Icon Resource Editor dialog consult the help file of IcoFX.