I cannot find out how to do it. I am annoyed that I am having to go through all this waste of time to find out and this is the third time I have had to enter the question.
Is this supposed to be helping me or making me more cross? What a waste of space.
I assume this is for the current version of Writer (if not, please specify). Go to Tools > Options... > [LibreOffice Writer] > Basic Fonts (Western):
Choose your fonts from the drop-down, then OK.
As for this site, if you put “default font” into the “search or ask your question” field in the green bar in the site banner, you’ll get quite a number of suggestions of previous questions about this. Sorry you arrived frustrated! It’s not so hard after the fist time…
~ Fairly calm in Edinburgh 