Oops, this has been quite long-standing without any answer...

I probably missed it because it was in the wrong section of the forums, so I moved it here now.
About the problem: For me editing the menu works - not as I would have imagined, but at least at all. I've successfully disabled and re-enabled the "education" section. However the menu is not updated live. In fact I had to reboot (!) to make it notice the changes. This is certainly less than cool, but the functionality is there. I've installed 10.3 and tried out the same there to rule out that this is a regression with the MATE 1.18 update - but no, MATE 1.12 also shows this somewhat lazy behavior...
frogprince wrote:So as root I type "mozo", and get the same menu, as root. But still, none of my changes show up in the menu.
Do not run mozo as root! The menus should be configured per-user (
~/.config/menus/) and changing the root user's menus is definitely not what you want.
Have you tried rebooting after making changes? For me that had the desired effect. No excessive testing was done on my part, though. It might well be that other changes than the simple thing I tested won't work at all and mozo is seriously broken.