From the KM wiki:
You can control the order of macros in a macro palette (or the status menu) by prefixing their name with two characters and a closing parenthesis (eg “01)” - two characters and a closing bracket). The macros will be sorted based on the code, but the code will be stripped off before display in the palette (or status menu).
For a great tool to aid in configuring the Palette for a Macro Group, see the Palette Organizer macro on the forum.