Won't remember screen resolution

Every time I start the game, it is at some resolution that is narrower than my ultrawide screen. I set it every time to the proper 3440x1440, click “accept” then “keep” during the countdown window. Play the game, exit out when I’m done. And every time I start the game, it’s at the wrong resolution.

11900k, 3080, 32GB RAM.

Set the wanted resolution in

Documents\Diablo III\D3Prefs.txt

Save it and it should remember the resolution. Good luck.