To avoid clicking the wrong icon, add visual separators. While the Toolbar Editor is open, right-click inside your custom toolbar. Select . This inserts a small vertical line to group logical sets (e.g., [Draw] | [Modify] | [Camera]).
While the native Toolbar Editor is excellent, some users feel it lacks advanced features like icon resizing or nested flyout menus. If you outgrow the native editor, consider these free/paid alternatives (mostly for Windows):
to save your changes. Note that some modifications may require a SketchUp restart to appear.