I have a spreedsheet with numerous worksheets and each has a header and footer with the same text in it. I have to change some of the text regularily (date etc) and have been doing each worksheet seperately.

Can I have one header/footer that appears on each worksheet

or

can I insert a user defined field into the header at the relevant place then use a cell in one worksheet to hold the data that will vary (ie the date), so I only change it once and all the headers change?

Seems an obvious thing to want to do but I cant find the tool/function to use and would appreciate your advise. Thanks.