Page Layout ⇒ Changing infoline in a presentation

[vsb1357]

I am using beamer class to prepare a presentation for a conference. I am using 'JuanLesPins' theme, combined with \useoutertheme{infolines}. The result is an infoline at the bottom of each page with 3 parts: the first contains the main title of presentation (as in the 1st page), the second is the subtitle, and third contains date and page number.
I want to get rid of the first part cause it is too long and cannot be shown properly in the specified space but I do not know how. I'd be grateful for any help.