Editing Players

I want to edit the ratings, names, numbers, etc. of players on some teams in the game. I'm trying to understand how to do this using the file converter.
What is the process to export players, edit them, and then import them? (either to the current league, or to use the file to create a new league).
I've tried to export players from the League Office screen (Import/Export dropdown), which gives me a .json file. I then run the .json file through the converter and get a .csv file. I edit the CSV file in Excel and save it as a .csv file. I then run the modified .csv file through the converter to get a new .json file. I then import it into the game from the import players in the League Office screen. I don't see any changes.
Is there a tutorial on how to do this? I can't do this inside the game, as that is very time consuming to update every player.
Thanks.
What is the process to export players, edit them, and then import them? (either to the current league, or to use the file to create a new league).
I've tried to export players from the League Office screen (Import/Export dropdown), which gives me a .json file. I then run the .json file through the converter and get a .csv file. I edit the CSV file in Excel and save it as a .csv file. I then run the modified .csv file through the converter to get a new .json file. I then import it into the game from the import players in the League Office screen. I don't see any changes.
Is there a tutorial on how to do this? I can't do this inside the game, as that is very time consuming to update every player.
Thanks.