Apple - Icons remains the same after I have changed the default program for opening the file

You can try to rebuild LaunchServices database from Terminal:

/System/Library/Frameworks/ApplicationServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user

Path to lsregister on Mavericks is:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister