You remember an annoying dialog box always pops up when you run MYOB? For whatever reason, Windows 10 felt your pain and decided to block it... Anyway, once we figure out what mechanism Windows 10 uses to block it, the rest is not so hard.
Just follow the steps in this page and MYOB will run again, without the annoying dialog box.
https://mynuuo.zendesk.com/hc/en-us/articles/360000764413-How-to-disable-UAC-for-a-specific-program