There’s no way to add more buttons or menus. Unlike the Office for Windows QAT, the Mac equivalent isn’t configurable at all. You might think those buttons above the tabs are a QAT. There is no Quick Access Toolbar (QAT) in Office 2016 for Mac. There are left/right buttons to scroll through the styles plus a down arrow to display a full list. The Styles gallery is a little different in Word 2016 for Mac. The Word Home ribbon looks much the same in Word 2016 for Windows (top) and Word 2016 for Mac (bottom) If you’re thinking of switching to a Mac computer, you can simply download and install Office for Mac without paying more.
One advantage of the Office 365 subscription/rental is that you can switch between Windows and Mac without cost. Stand-alone, single purchase Office 2016 for Mac will be available in September. There’s a 1.1GB download, then installation. Office 365 customers (personal, student or organization) can go to their My Account page, choose Office 2016 for Mac. That’s a nuisance because, until now, we’ve been able to tell Mac and Windows versions of Office apart simply by the ‘year’ – for example Office 2011 always meant the Mac version because there was no ‘2011’ Office for Windows. One for Mac and the upcoming Office 2016 for Windows.
