It works in another world, able to config all the stuff and the sorts. But cannot get it working on another world.

Did you ever move the world or delete anything from it?
How did you add the pack to the world?
What version of Minecraft & MobCaptains are you using?
Singleplayer or server?
Other mods, plugins or data packs?
What loader? Vanilla? Paper? Purpur? Fabric? Forge?

Weird, probably an incompatibility with one of the other mods.
You could try to run /function ps-mob:load to manually trigger a reload of just MobCaptains but unsure if that will help.
If that’s not it, this is most likely something I can’t fix on my end since the mod is a data pack under the hood, meaning it only relies on vanilla mechanics.

1: Not that i know of
2: Using ATLaunchers "Add mod" button and using the Modrinth option
3: Version is 1.20.6 and the "MobCaptains-mod-v3.3.0.jar"
4: It is single player with PnP.
5:

6: Fabric

Working on one world but not any new world i make.

Huzzah that worked fuck yea.

i tried looking for a command like that but couldnt find it at all. IDK how youd do it, but something like an FAQ or "try this if its not working" could probs go miles. Or there is one and im blind

No, there is nothing for that specific command but the vanilla game makes sure that that command runs when joining the world/restarting the server, so it shouldn't be necessary.
Mods break a lot of things though since they can literally change everything about the game. If I revise the description or link to an faq I might include it 🤷 thanks for the suggestion.