I’m trying to print. Why does it enlarge my doc to a size that can only fit one word on each page?

For example: the first word, Chapter, changes from a font size of 12 to about a font size of 80.

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Is the paper size shown in the printer dialog the same as the paper size in your document? If you have an A4 or Letter document and the printer is set to Label 73mm x 21 mm you will not get many words per page, and the preview will appear to show very large words.