The steps to add, remove or arrange the buttons of the toolbar are
1. Right click on the toolbar. The context menu shows up.
2. Select "Customize..." from the context menu. A Customize Toolbar palette pops up.
3a. To add buttons to the toolbar, find the button from the palette and drag it to wherever you want inside the toolbar.
3b. To remove buttons from the toolbar, drag the button that you want to remove from the toolbar to the palette.
3c. To arrange buttons in the toolbar, drag and drop the button to a new location inside the toolbar.