Customize Firefox controls, buttons and toolbars {web link}

Type about:customizing<enter> in the address box.

Note: about:customizing is no longer present in Firefox 47+ releases.

• Press Alt or F10 to bring up the Menu Bar.Then View > Toolbars > Customize.
• Right-click on a blank spot in the toolbar and select Customize.

In the new window, look for the icon. When you find it, hold down the left button on it, and move it to where you want it to be. You can move any of the icons you want from here, but; some icons are locked in place.

There is also a Restore Defaults button at the bottom right.

As a shortcut to customizing, the right-click context menu for most toolbar buttons has a "Remove from Toolbar" item. For individual bookmarks, the wording is different (the bookmark actually gets deleted).