I'm running an nvidia card on X11 Plasma 6, with a 4K monitor alongside a QHD monitor. Both monitors are the same physical size, despite being different resolutions, so in the nvidia settings app, I've got the second X screen setup to generate 4K but downscale it to QHD in the output. It makes the second screen slightly blurry, but it's worth it for the ability to move windows back and forth without dealing with different resolutions.

The problem is, no matter what I do, I can't make the changes "stick". The nvidia applet has an option to save it to the x.conf file, and I've verified that it has done so in a text editor. But every time I boot, I have to change it in the nvidia settings applet again.

Is there something I'm missing with the way arch/kde handles x conf files? How do I make it stick between reboots?