Seeking guidance on usage of "Auto Approve" checkbox on EX Transaction Definition page

Looking for guidance on how to use the "Auto Approve" checkbox on the Transaction Definition page in Expenses.  In particular, we have a testing issue that, I wonder, could be resolved by using the Auto Approve options.

In our 9.2 (Image 11) environment, in the EX module's "Transaction Definition" page (Product Related > Expenses > Management > Approval Setup > Transaction Definition", we have 4 active Approver Types on this page, _none_ of which has the "Auto Approve" box checked. 

In testing, we have identified an issue, as follows:

- Submitter submits expense report.

- HR Supervisor reassigns approval to another approver.

- Reassigned approver approves expense report.