I've been streaming church services for 15 months now. I've never seen OBS randomly change settings.
Either PC corruption (causing disk writes of a settings change to fail)
or something (AV or security software, or malware) interfering with disk writes (malware would be doing more than the settings you mention, so possible but unlikely to be cause)
If you change settings, are all changes not saved? [indicates one issue]. Or are only some settings changes not saved?
[as I type the above, a more likely culprit comes to mind]
Or are you logging in as different users (and each users profile is unique, and most OBS settings are NOT shared). See thread(s) here on multi-users sharing a PC [basically OBS isn't setup by default to allow different users to log in and share a identical OBS settings environment]. There are work-arounds, but they have nothing to do with OBS and requires understanding Windows OS profiles, where files saved, etc