Why does Windows 10 Compatibility mode pop up a UAC prompt?

I have a program on my Win10 machine that I run in WINXPSP3 compatibility mode. I set this up while logged in as admin using the "Change Settings for all users" dialog.

So when I run the program while still logged in as admin it pops up a UAC prompt (but doesn't ask for creds), so I click past and the program runs fine. I did not set "Run as Administrator"

Then I log off and I log back in under my normal-rights user, I run the program and it crashes on launch--no UAC prompt--the same error that made me go to compat-mode in the first place. So it clearly isn't even using compat mode, though I can look at the properties and see the greyed-out-checked box (because it's set for all users).

So, two key questions:

1. Why would compat-mode require elevated rights in the first place?




2. Why isn't the "...all users" setting working at all?

Answer

Only windows 7 and up have separated administrative rights from user rights.

When you use Windows XP or earlier as compatibility mode, you need administrative rights because in those operating systems administrative rights were always present and as such, it is likely that the program requires administrative rights if you need that level of compatibility.