As you know whenever any window is displayed in Ubuntu, the three universal buttons Close, Maximize and Minimize are displayed on the right side by default. Ofcourse this is standard, but if you are left handed person or just want to change the buttons placement to the left side then this guide is for you.
The following screenshot shows the regular window which has all these three buttons on the right side.
Edit the Gnome configuration by launching the gconf-editor. To launch the gconf-editor, press Alt + F2, then type gconf-editor and hit Enter.
Here, navigate to the apps > metacity > general option in the left side window and then locate the button_layout option in the right side main window. Double click this option and set its value to close,maximize,minimize:menu .
That’s it, now you will notice that these three buttons appear on the left side of the Ubuntu Window.