Why does document start at very top of page when printing? looks good in preview
Don’t repeat the question but describe your concern. Are you talking about a Writer, Calc, Impress or Draw document? What have you done resulting in this behaviour? We can’t help without a minimum of information among which your OS, LO version and locale.
Possibly different page layouts were defined in the menu Format -Page Style... (Legal) and in the menu File - Printer Settings ... (Letter), or in the printer itself.
LibreOffice tries to print in the same paper size set in menu Format - Page Style…. But if in the Print dialog you confirm the paper size set in the menu File - Printer Settings… …
Tested with LibreOffice 6.4.7.2 (x86); OS: Windows 6.1.
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