membership pro switching 5 year finite membership to 1 year

I am trying to give a 5 year option to my users for a discounted rate, however where it has the number of years box it changes back to one year every time I go away from the page and of course there is no submit button on that page. Is this a bug or is there a reason for this? we want to be able to provide discounted 5 year memberships to try to get initial capitol.