You've shared a Doc or Sheet and want to see what changes have been made after a few days. Utilize "Revision History" to see all the changes that have been made.
Go to File > Version History > See Version History and you can see what changes have been made to the document, when the change was made and the person making the change.
Not only that, if you want to restore a certain paste version you can do this with the click of the mouse.