Make hidden fields on the edit form for each thing that can be changed, with the same values as what was pulled from the database.
When an admin submits the script to be updated,
if($_POST['original_value'] != $_POST['new_value'])
{
insert into database the admins name, the feild they changed, and the date and time they changed it.
}
you would have to repeat that 20 times changing the names within the if the match the names on the form. Or make 2 arrays with 20 of the names and use a for loop 20 times to load
if($POST[$array1[$x]] != $POST[$array2[$x]])
Then you can search who did what by pulling the admins name, the date/time, or feild that was changed. I hope that made any sense.