When copying a Form to use and send to a different person, some of the questions disappear

I have been using forms to send out questionnaires.  I have a couple of template forms, which I copy and send out. This has been working perfectly until the last few months.  Now if I copy a form, some of the questions disappear and I have to go in and edit the form, which is time-consuming.  Has any one else had this problem and if so, how can I resolve this issue?