I'm having the same issue as Ace76inDC, no matter if I open the in-game dialog or manipulate the Settings.cfg within the game data directory for DistantObject, the desired settings do not persist (it reverts in-game to the default, regardless of the config). It seems to effect every option, mostly enabling Distant Vessel Rendering and turning up the Maximum Sky Brightness to 1.0.
My KSP.log file doesn't seem to be working, the last edit time was years ago. Here's my MiniAVC.log instead, if that helps: https://pastebin.com/1NpR3eVw.
I launch the game via Steam with the launcher bypass command line.
Hope this helps!