With the list setting: Create items and edit items that were created by the user, it is not possible to let another user to update the item even we give to him Full Control to the item.
With the list setting: Create and edit all items, the creator can edit all his items even we give to him Read access to the item
This has been tested in 2010 and 2013 on Premise
What is the best solution to avoid the user which we have change his permissions to Read access to Edit his item?
Best regards,