maximise cricle is not showing up on imac

What are you talking about? What is a maximise cricle?

If you are referring to the green bubble on the left side of a window's title bar (next to the red and yellow ones), note that this won't show up in all windows. If this isn't showing up in one particular window, note that some windows are not resizeable, and thus do not have such a button. Of course, if this is happening with all windows, there's a problem, as it should show up in most. Can you clarify?

I'm not sure what an "audio bar" is.