XYplorer Beta Club

How do I customize / change the toolbar icon? Thanks

you cannot change the icons for default toolbar buttons. (I could suggest XYSkinner, but I'm afraid it's hopelessly fallen to far behind)

But the Custom Toolbar button icons can be customized.
(You'll know whether a button is customizable If you can (CTRL+) rightclick it and see a menu with at least Click/Edit/Customize...)

So, just hold CTRL and rightclick the button and pick "Edit". Then place th path to your desired icon in the "Icon" textbox. XY native variables like <xyicons> are supported. Eg, <xyicons>\cfi\xy.ico.
Also, you can prepend a : behind default toolbar button names to use the icon of that button, eg, :select (choose Customize Toolbar from a ctb rightclick to get the name for buttons in square brackets)