After I upgraded to the latest version of Ubuntu, I noticed the interface is different. It’s called Unity and it’s a minimalistic interface with large icons and auto-hiding menus.
I like having the Applications, Places, System menus at the top and visible. I prefer the Gnome interface because I knew where everything was and the menu does not auto-hide.
You can go back to Gnome through the log-in screen that appears when you boot up Ubuntu. If you are already in Ubuntu, you can log out by clicking on the power button and selecting Log Out…
At the log-in screen, choose your user name and on the bottom of the screen there is a drop menu with Ubuntu selected. Choose Ubuntu Classic and log in and now you’re back to Gnome.