InfoPath Dev

Dear Clay Fox, I am still confusing where to set it? This "Overwrite existing file?" checkbox is on "Save As" window when I save an infopath browser-enabled form, the "Save As" window was called by form service. So I don't know how and where to set it. The screenshot as follows:    

When I save a new infopath form(browser based) the "Overwrite existing file?" checkbox is checked by default on poped up "Save As" window, what I want is to set the checkbox is unchecked when "Save As" window pops up. I tried but failed. Can you give me any solution?? Thanks very much!