change default font in LO 6.3

All answers to this question give outdated/wrong/unworkable answers.

Have gone to Tools/Options

How do I change default font (for all new documents) in Libre Office 6.3?

Learn and use styles.

… and how to define a (new) default template or see my comment to @Hrbrgr’s answer

Open Writer with a blank page. Now change all the desired styles. You now save the modified page as a template. Please do not forget to activate the checkbox “As default template”.

See also: English documentation

… you may also use Tools -> Options -> LibreOffice Writer -> Basic Fonts (Western) to modify your default fonts, without defining a new template (assure to have opened an empty Writer document for availability of the configuration options for Writer).

@anon73440385, thanks for the support.