how can I insert page numbers into the entire document

I am working on a document and am only able to insert the page number one page at a time. How do I fix this?

This question has already be answered huge number of times. You should have used the search box to find relevant questions and answers.

To make it short, page numbering is a property of page styles. From your question, you’re a newbie and likely use only the Default Style page style.

Open this page style (I leave to you as an exercise to discover how to do that). Enable header or footer, depending on where you want the page number. Close the page style.

Click in the header or footer area of your document (it is easier to locate these areas with View>Formattaing Marks). Insert>Fields>Page Number. Format the paragraph where you put the page number as you like (left/right justify, center or any other layout).

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