Same field on different pages

Hello,

I have a group of pages based on different termplates, but they all have the
same header. In the header of these page, I have a scrolling text. I would
like this scrolling text (which is a bigtext field) to be the same on all
the pages. When I change the scrolling text on one page, I would like the
modification to take effect on all pages. 

Is there a way to do this?

 

Thank you.

Laurent