Change High Sierra iTunes 12.7 Icon to old blue version

The iTunes icon for 12.7 is a multicolor unappealing icon, especially when it sits in the dock. I've used the old blue iTunes icon version since before Yosemite by replacing the new versions with the blue version. It used to work by opening "Get Info" and pasting the old icon in the upper left where the new icon was located. Trying to do this in High Sierra, the "paste" function is greyed out and only the "copy" is functional in the pull down menu. The ⌘V also doesn't work. Have they locked out the option to change the icons on the Apple apps? Is there a work around?