In some cases I have been able to delete the computers cookies and delete the history also. It does take some time but then I feel a little more secure, especially if I have looked at anything financial also.
It is way too easy to install a keyboard logger on public computers. You should never use them for anything that requires you to login or provide any other private information.
To the OP, I would for sure file a police report, not much will come out of it but at least you have a record that you can use with United.