I changed the configs in-game with "q" button in the game-menu but it doesn't save. I checked the config files and they were already the same as when I saved it in-game but to no effect. I'm running 1.18.1 with Quark 3.1-340. I also have OptiFine. Nothing crashes, just the config won't save. I already deleting the config file and reloading the game.

This was fixed in more recent versions.