I don’t really think you can turn volumetric clouds off in the graphic settings, only to low.
You can turn them off in developer mode, but then you have to have dev mode on all the time and then logbook doesn’t work I think.
Actually, it is somehow possible to have some dev options change and left on (like FPS etc), but it’s kind of hit or miss. There is a save settings option in the dev menu but not really sure how it works. May have something to do with how you turn dev options off. I’ve played with the settings and had things stuck on or off. Again the combo of things I mentioned (save settings, how you turn dev options off) and the setting that is on when you shut down the sim. Also activities that force weather. No real guide or manual and results are very hit or miss. Only thing that works somewhat consistently is leave dev options on and volumetric off. But then no logbook.