When OA first finds a device it tries each credential set (stored in the credentials table) until it finds one that works. Once OA finds a working set it records which set worked last with that device in the "credential" table. The next time an audit runs OA will try that set first to speed up auditing.
Select Admin -> Database -> List Tables from the Open-Audit menu, then click Details for the Credential table to view the stored sets
So, although you have deleted or altered the existing credentials sets, OA has stored in this table the set that last worked with those devices. You can clear the entire table by clicking the red trashcan icon at the top of the screen in the Current Rows text field. This will reset OA’s memory, the next audit might take a little while longer to run as OA works to determine which credential set works with a given device, but it won’t try to reuse the old credentials.