Ubuntu’s window buttons (Minimize, Maximize, Close) are a little different. They are on the left corner of title bar. You can change them if you’re comfortable with buttons at right top.
In Unity Dash Home search for and open “dconf Editor”:
In next window, navigate to org/gnome/desktop/vm/preferences, chance the value of “button_layout” from “close,maximize,minimize:” to “:minimize,maximize,close”
That’s it! Enjoy!