Not all the icons have changed after installing a new icon theme in Lubuntu

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http://askubuntu.com – I have installed an icon theme in Lubuntu. Icons have changed but not every icon. Folder icons are the same but there are many more icons for music folder, video folder etc. Opera has new icon, but they didn't change. What should I do to change all the icons from the new icon theme? I am using PCManFM as my file manager in Lubuntu. (HowTos)