Can't change fonts

I see where to change fonts, but the changes aren’t taking hold. Maybe a stupid question, but do I need to copy the Google Fonts code (ie, : google(@import url(https://fonts.googleapis.com/css?family=Arimo);),Arial) and paste somewhere (and if so where)? Or do I just select font and styling and hit apply?

I’m using the Headway Theme, so already using Google Fonts from the Headway backend.

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