where is theme settings in ubuntu 18.04?

I have just upgraded from 16.04 to 18.04. My installed theme was Flatabulous. My desktop looks really weird. I can not find theme settings in System Settings. Have is it been removed? How am I supposed to change theme and icons?

There are a number of Theme apps that are not installed by default. You can list them by hitting the All Applications button at the bottom of the Launch Panel, and typing theme.

The list includes:

• Themes - Manage themes to change how your desktop looks
• Appearance - Change the background and the theme
• Gnome Tweaks - Tweak advance Gnome 3 settings
• Customize Look and Feel - Customize look and feel of your desktop and applications.

When you type in the All Applications menu it searches your installed application as well as the repository for matches.

The most common and effective tool is gnome-tweaks

$ sudo apt install gnome-tweaks