Reason they don't apply is because the apps have newer specific names to the image file. It ain't "Fandango.png" anymore. And you have to replace the old .png file with the new one in the app's original folder which you can find via SSH or better iFile. Find the App's folder and find the file that represents the icon image, add a "1" at the end of the original file's name or just delete it. Then add the new icon you want for it in the folder and use the previous name you saw in the file you renamed or deleted. For the default device apps, the icon's name is "icon@2x.png". For AppStore apps or any other third party apps, the name can vary depending on what the developer named it.