Q: Changing Finder Icon - El capitan

The instructions I am referring to are from here:http://osxdaily.com/2014/05/01/change-finder-dock-icon-mac-os-x/

Other folder and icons that I wanted to change was a matter of opening the custom (picture I want as the icon) .icns file , right clicking - > get info, click icon -> edit -> copy

Open application or folder that I wanted to change and follow the same get info path, expect paste at the end.

This method does not work when trying to change the finder icon, actually any of my default mac applications (finder, launch pade, ect. )

This did work for changing my finder icon, thank you. I had changed my google chrome icon earlier but when I took google off my dock and reopened it it had went back to the stock icon. Is that just the way it works or is there someway to make it stay even if i dont keep the app in my dock?