Everyone who’s ever edited a document: oh there’s now a blank page at the end of this Word document, time to get rid of that!
Word: no
Everyone: please delete
Word: shan’t
Everyone: * frantically presses delete backspace delete*
Word: answer me these riddles three
If you go into the Styles menu (either the F10 or F11 key, I forgot) you can change the font of the Default Paragraph (or something akin to that name) to the font of your choice.
I haven’t used LibreOffice Writer in a while, though, so I’m not sure if that change will stay between sessions, but it should.