Hi David,
Thanks for posting your question. This is a known limitation of A360, you can only search files that you have uploaded and own. Can you post this to our IdeaStation as a future suggestion. Then we can open this up to comments and kudos from others.
http://forums.autodesk.com/t5/a360-drive-ideastation/idb-p/202Thanks and also if you have not had a chance be sure to check out A360 as well. It's project based and has multiple levels of search. Here is the link to check it out.
http://autodesk360.comThanks and let us know if you have any other questions.