It is not easy to install Ubuntu Tweak in Ubuntu 16.04, and it is troublesome to change the theme. Let's follow the Unity Tweak Tool. To adjust the Unity desktop environment, it is recommended to use the Unity Tweak Tool, which is a very useful graphical management tool for Unity, which can modify the number of workspaces, hot areas, etc.
This article http://www.linuxidc.com/Linux/2015-12/126158.htm is currently not suitable for use under Ubuntu 16.04.
Although Unity Tweak Tool is one of the important tools for Ubuntu Linux, it is not pre-installed. In order to freely customize the Unity desktop environment, let's introduce how to install the Unity Tweak Tool in Ubuntu 16.04.
linuxidc@linuxidc:~/Desktop$ sudo apt-get install unity-tweak-tool
Reading package list... Done
analyzing dependency tree of packages
Reading status info... Complete
the following [NEW] software Packages will be installed:
unity-tweak-tool
upgraded 0 packages, installed 1 package new, uninstalled 0 packages, and 16 packages were not upgraded.
A 376 kB archive needs to be downloaded.
After decompression, 2,864 kB of additional space is consumed.