Try to copy the file where it is allowing you to do it? If there you are able to read it then copy the file to a directory that the writer is granting permission to do it.

The user who is having the read only right to copy the documents onto another notebook as well as enchanting it with them. The other users who have the write to access to these documents so unable to put the password for protecting the documents in it. This is also a big security risk, so I would like to know whether we can restrict the other users from copying any of the documents from the file.

As I have said, if anyone who is having the read only permission to the file, then they are able to copy it to anyplace where they are having the write permission.

In short, if you desire them to be able to read the document only, rather then allowing them to copy it. You are not able to put control over your files.