How did I do this! - Content titles

Hi everyone.

Little embarrassing this, but in my defence the document template I created is coming on ten years old!

I have a solution in place for creating headings on each page. Whereby, I fill in one box the name of the title, which in turns creates a title in another text box. This then repeats page after page, until I create another title where by it chanegs. For the life of me I cannot remember how this is achieved and i want to start from scratch as I have like a million colours in the document that cannot be deleted for one reason or another and it annoys me!

Can someone give me a pointer?