Mac app toolbar buttons don't always tell us exactly what they do. Add text labels to toolbar buttons and know for sure. Quick and easy.
Add Text Labels to Mac App Toolbars
Hold the Command key down to drag things around in Mac app toolbars
Many Mac apps have toolbars-- Mail, Safari, Pages, Numbers, Keynote, and many more. The tools on such toolbars can be rearranged via Command-drag.