Unity Tweak Tool is a settings manager for the Unity desktop. It provides users with a fast, simple and easy-to-use interface with which to access many useful and little known features and settings of the desktop environment that one may want to configure.
Install Unity Tweak Tool on Ubuntu 15.10
Open the terminal and run the following command
sudo apt-get install unity-tweak-tool
This is really useful tool if you want to play with unity settings