I’ve written a document which is a stage play and in the header I want to enter in the act and scene that corresponds with each page, but whatever I enter into the header will appear on all the headers on every page. I searched for help on Ask Libre but couldn’t find a solution to my problem. Is it possible to have different text on different headers in the same document?
This is the current act/scene breakdown of my script by page number:
Act I, Scene 1, p. 1-24
Act I, Scene 2, p. 25-40
Act II, Scene 1, p. 41-62
Act II, Scene 2, 63-64
Act II, Scene 3, p. 65-70
Act II, Scene 4, p. 71-74
What I need is for those act/scene numbers to appear in the correct headers for each page.
Do you mean a change of scene causes a page break?
The purpose of header is to do what you’ve seen on your document. To do what you want, don’t use the header.
What you want is to use is the Heading paragraph style. (Header and Heading are potentially confusing, I know.)
Just type the heading into the main area of the page, and (while the curcur remain on that line) change the paragraph style to Heading 1. I hope you can figure out the rest.
The short answer is yes.
Now the procedure to do it depends on how you structured your document.
The common way is to use Heading n paragraph style on the title introducing a new act (Heading 1) and scene (Heading 2). With such an organisation, you can insert cross-references in your header, e.g. to the scene/act number or title, and have them dynamically captured at start of every page.
Another simpler way occurs when you cause a page break at the beginning of every act. You can then create a separate page style for every act and have independent headers. You can also have dynamic field insertion like in the previous proposal which works with only one page style.
Detailed instructions can be given after you edit your question to provide more information on the present structure of your document(= do not use an answer for that).
EDIT 2018-08-10
Use the Heading n style family to automatically number your parts: Heading 1 for acts, Heading 2 for scenes. Arrange the formatting the way you like. In Tools>Chapter Numbering, select Roman numbering for acts (level 1) and common numbering for scenes (level 2) and set prefixes in Before box as "Act " and "Scene " respectively (without quotes but notice the space).
Modify the page style for the synopsis (you may have other page styles for title page, introduction, cast, …) to enable header – you likely already did it. Click in the header area to create the dynamic “title”. Insert>Cross-reference; in Document tab, click on Type Chapter, then on Format Chapter number. If you prefixed the number with "Act ", there is no need to add it manually in the header.
Unfortunately, only the first Heading n of the page is captured this way.which means you need to structure a bit the use of your Heading n so that you can retrieve both Heading 1 and Heading 2 numbers.
Manage to have both Heading 1 and Heading 2 trigger a page break (in Text Flow tab of their definition) so that both won’t appear simultaneously on the same page. For instance, you can format you Heading 1 so that it looks like an intermediate title page. With such a configuration, you can insert 2 cross-references to Chapter number, the first limited to Level 1, the second with Level set to 2. They now display different information consistently.
I wonder if the OP is able to follow you. He seems like a beginner in word processing.