ATTACH DOCUMENTS

Hi Experts,

I'm trying to attach a document in BPC NW 10 by web administration. I'm having a security problem. When a use attach a document, all users can see it. I know that when you attach a document, there is the option "Sharing". Look my example: the only user ho can see the document is the user ho attach it (in the ex. user 1). But all users can see it. Does somebody has documentation about it or somebody knoy what can be happend?

Thanks!