Is Adobe Sign really secure?

When i send out a template of new hire paperwork, i set up the KBA security for the recipient, however when they submit the paperwork and i get the notification email, i am able to open the PDF's of all the forms without entering a password? So how is this secure?  The forms that i am getting returned are the ones with the SSN, birthday, etc. on them.  Is there a way to set it up to where we have to enter a password to view the document?