So i'm trying to save a rank in the config but once the u set a user another rank the old rank's data gets removed and then it gets replaced by the new rank's data.
Are you saying that's what you did, or is that what you're trying to do? Also, show your code. You should only need to use Config->set() with an identifier for the player and save the config if you want to overwrite their rank. If you want to add to it, just get their current data, and append it with array_push if it's an array, or something else depending on how you stored the data.
what i'm trying to do and i only have a code that sets a player the rank and to change the chat format i don't know how to work witht config part that's why i'm trying to figure out