I recognize the urgency to address the transaction created by an unauthorized user, as this situation is serious and concerning, Ruth42.
If you are viewing the Audit Log, please note that System Administration is not a user but an automated bot that records changes made by the system itself.
This can happen for several reasons, such as changing a customer's address or events for every transaction tied to that customer or vendor. The program logs it as a System Administration. For more information, refer to this article: Use the audit log in QuickBooks Online.
As a precaution, I recommend changing your password to something strong and unique or enabling two-factor authentication for all users.
While you're unable to contact support within the system, we can contact our support outside of QuickBooks through this link. You can also reach out to our security team directly at security@intuit.com to report this situation.
I'll be here if you need more assistance regarding this topic.
