Why does Administrator approval pop-up?

GARoss said:

I don't know what setting I've changed to make this popup requiring password for software install. Before the popup required a Yes or No to install, not Administrator password. I am the owner, administrator & the only user on this PC.

It looks like you have done two things, the first was to enable the built-in Administrator account (that's the account named Administrator.) The second was to change your own account from an administrator to a standard user.

To fix this you need to sign in as Administrator and set your own account back to being an administrator.

Great! You're lucky you had the built-in Administrator already enabled, otherwise it would have been much more complicated to fix :)

What I normally recommend is that you make a second local administrator account for maintenance/repairs like this. Then you can disable the Administrator. It's disabled by default because it isn't restricted by UAC, it's safer to use a normal admin account.