Out of interest why do you only have one account for exams when students are saving work to it?
We set up individual accounts for users when they need to create work, This then is saved to that users area. The Exams officer then has access to the accounts work areas so they can do what they need to with the exam work.
This stops students deleting other students work etc.
Any online exams we log them in as a single user as usually all work is done within the exam portal.