In Audit Log, User indicates that it is System Administrator. Who is that? It does not list my name nor my wife's.

Hello, hippler1. 

Let me share some insight about System Administrator in Audit log in QuickBooks Online. There are several reasons you might see changes posted in the QuickBooks Online Audit Log as System Administration. 

If you modify an entry that also impacts another entry in your data you will typically see a System Administration posting in the Audit Log. For example, if you edit a payment that was attached to an invoice, and attach it to a different invoice, you may see System Administration in reference to the invoice associated with the changed payment. In some cases, it may be reported as an "Indirect Edit" by the User who initiates the change. 

For more detailed information about audit log, please refer to these articles:  

• Use the audit log in QuickBooks Online 
• How to view transaction changes in the audit history

Please touch-based with me if you need anything else in QuickBooks. I'm here to lend a hand. Have a great day, and stay safe!