Honestly, Joanne, if my steering wheel was trying to turn itself, I would notice, even though I'm physically well. In particular I'd notice it if was aggressive as you describe, but I'd notice even a twitch.
I can't stand the thing. I was spooked by it on my test drive. When I got my car home for the first time I went for a joyride, and about 40 miles from home I pulled into a layby, read the manual, and found out how to turn it off. It has not been back on since apart from a couple of times when I drove off forgetting to cancel it, and didn't realise till I felt a slight wheel twitch. (Most times I've forgotten it, I've realised because I've seen that the LKA icon is white rather than yellow, and have turned it off before it did anything.)
It doesn't do anything when it's off. Not a damn thing. Believe me, I would notice. There is either some setting in your car that is turning it back on, or there is a fault. It is not normal to experience what you describe with the system disabled using the infotainment screen.
Are you sure the TJA is not activated? Are you sure that you press the brake pedal to put the car into Ready mode before you go into the menu to disable the LKA, and that you tap the "confirm" tile on the dialogue box that comes up? Are you remembering to do this every time you sit down in the driver's seat, even if you have only got out for a moment and the car hasn't been turned off? Are you continually aware that the LKA icon is yellow, and ready to do the turn-off routine if you see it white? Because that's what it takes. But if you do that, at least in my car, it goes off for that journey. Until you sit down in the seat for the next time of course, when you have to do it all over again.