You should find it in the Word toolbar that will install under Trados. Almost at the end of File, View , Tools etc. I f you cannot find it, you can use the shortcut: Alt + Control + U and that is Fix document.
Hope this helps
For the sake of accuracy, that's not a toolbar. That's the menu list (menu bar?) The toolbars are the thingies with graphical icons a bit further down, and incidentally, Trados has one of those as well, without a fix documment icon/button.