Yes when you see your icons are not a beautiful or any reason you want to change the icon in ubuntu. This article will guide you 3 simple way to do it.

Change the icon by changing the theme

Changing themes for Ubuntu Ubuntu is wearing a different shirt. It changes the look and change your icons are added theme that. Read the article Change the theme for Ubuntu to know how to install and use.

Change the entire icon

This is similar to the above theme settings.
Step 1: You go gnome-look.org to download the file menu icons and icon you like about. Unzip and copy the folder .icons in home (Ctrl + H to show hidden folders, if you can not create).
Step 2: Use Unity Tweak Tool to change the icon.
For example, just download and copy your icon set Transparent Tiles v4 Blue in ~ / .icons then go to the Unity Tweak Tool icon select this icon set.

Change the path icon

If some of the icons in the theme you are using is found invalid, you can change them manually to the desired icon. Have 2 how you can change the icon of 1 program:

How to 1: Change the * .desktop
Step 1: Open terminal (Ctrl + Everything + T) and move to /usr/share/applications/ command:

cd /usr/share/applications/

Step 2: Change the * .desktop (For example, instead of vlc icon, the file will be vlc.desktop)

sudo gedit vlc.desktop

Step 3: gedit open vlc.desktop you locate the line Icon=vlc. These are the icons for vlc stream. You replaced with the path to the icon you want (CEO: /home/nguyenvanquan7826/vlc_icon.png).

How to 2: Change the file directly icon
You open nautilus by root with the command:

sudo nautilus

You go to the folder icons, usually /usr/share/icons or /home/nguyenvanquan7826/.icons (/.icons in the home directory) then find the theme you are using. In this folder will be placed icons of different sizes. Often icon of the software is 48×48 and now copy your icon file overwrite the old icon is ok.
For example, the icon of the software with its themes Numix like this:

Read more: Flat interface for Ubuntu