To export:
Click on "I/O", then "Export."
Select "Single" if you are exporting one player or "All Visible" to export all.
Make your edits in Excel and save as a .csv
To import a single player:
Click on the player and highlight the entire line.
Click on "I/O", then "Import."
Select "Overwrite Existing" and choose your file.
To import all players:
Click on "I/O", then "Import."
Select "Overwrite Existing" and choose your file.
With large files, it may take a few minutes to replace everything.