Hi Greg and welcome to our forum,
It's the same as Internet Explorer's. I'm not sure how easy it is to modify these but they are in the Internet Explorer cache. Check out Tools->Options->General and click on Internet Options. Select the Content Tab and click AutoComplete. The 2nd checkbox is for Forms. This is what controls AutoComplete for InfoPath.
Patrick Halstead [InfoPath MVP]
InfoPathDev
Patrick Halstead
Project Manager at Qdabra