UAC keeps resetting on Windows10

Solution 1:

Open gpedit.msc and navigate to Computer configuration -> Windows settings -> Security settings -> Local policies -> Security options. Under that, disable User Account Control:Run all administrators in Admin Approval Mode.

Here's what the documentation for Admin approval mode says:

If a computer is upgraded from a previous version of the Windows operating system, and the administrator account is the only account on the computer, the built-in administrator account remains enabled, and this setting is also enabled.

This is indeed the case for me - I have upgraded from Windows 7 Ultimate -> 8.1 -> 10, and mine is the sole administrator account. If that's the case for you too, well - seems this can't be fixed without a fresh install of Windows with a separate administrator account.