How to Force Specific options.txt Settings on First Launch
options.txt holds client-side settings like keybinds, GUI scale, render distance, and language. Configured Defaults can seed this file so players begin with your chosen setup instead of vanilla defaults.
Placing the File
Put your finished options.txt directly inside the configureddefaults folder at the root level, not in a subfolder. The mod looks for it at the same path it occupies in the live game directory, which is the instance root.
What Gets Applied
On launch, if no options.txt exists in the game directory, the mod copies yours in. If a player already has one, it is left untouched, so their personal keybinds and video settings survive. This makes it safe to include in a distributed pack without wiping anyone's preferences on update.
Caveats to Watch
Some options are tied to hardware, such as fullscreen resolution or GPU-related toggles, so forcing them can cause problems on machines different from yours. Stick to settings that travel well, like language, GUI scale, and keybinds. Also remember that Minecraft may rewrite options.txt on exit, so the file in configureddefaults is only a starting point, not a permanent lock. If you need a setting to stay fixed, handle it through a mod that enforces it rather than relying on the initial copy.