Windows Defender Cannot Be Turned Off

As I use a proprietary antirvirus, and on a whim, I just thought to check my Windows Defender setting, only to find to find that it was turned on*. (I could swear I turned it off, sometime in the past. I was further surprised to find that the On/Off button is disabled--so I CAN'T turn it off!

I'm further surprised to find the notice, under Settings/Windows Defender, which says "You can turn this off temporarily, but if we find that it is turned off for a while we'll turn it back on again, automatically." (One mystery solved*)

As I understand it, Windows Defender is merely Microsoft's own notion of free antivirus software--so when Windows turns Defender on again, this means I not only have two antivirus packages running (and possibly interfering with each other--involuntarily) but also that I now seem to have no choice in the matter--unless, of course, I permanently uninstall the antivirus software that I paid good money for.

Questions: How do I re-enable the Windows Defender On/Off button; and
How do I DISable Windows ability to turn it on again?

Oh! Instant discoveries!

When the Settings window opens, it may look like it is fully open, but it is only half-open. Lo and behold, way down at the bottom of the window (when, that is, you finally realized what's going on) and off the bottom of the monitor altogether, below the "Versions Info," are three words that anyone would think deserve placement right up top: "Open Windows Defender." (They look, more to the point, greyed-out, hence, the link looks disabled.)

Imagine my further surprise when a notice appeared saying, "This application has been turned OFF and isn't monitoring your computer."

On, or Off, Microsoft. Please make up your mind. (and please put these things where people expect to see them.)

Accordingly, I have myself solved one of the problems in my previous post. As for the second, this may now be for me a moot point, but it remains: Is there a way to ensure Windows doesn't turn Windows Defender on again, without the users input or knowledge?

"If you have a 3rd-party AV installed, it turns Defender off. It will be turned back on when you uninstall the 3rd-party AV."

Hello simrick.

So, in the interval between uninstalling one AV and installing another, Windows Defender self-activates and de-activates?

THAT, mon ami, is a critical piece of info. Thank you!

(You should get a job with Microsoft's design team.)