Can someone help or guide me in editing some positions in the game, so that they remain forever and I don't have to be editing every time I start a game. Please I'm a newbie at that.

Typically creating a league creates an exported xxxxx.json file. After you modify your players to whatever you're lookign to do you can import it on top of itself to do updates, or you can use the file as a player source to create a new league.

May help if you post your .json file so folks can take a look and see if there is anything off with it.

I think I do. but when I create a new league there are only some modified players

I can't upload the file

I can't even do it in the league that I create to edit, they get edited ...