can not keep save font in a doc

I save in Arial 20 point but is always opens in Liberation Mono 10pt. I have changed the font many times via tools/options/writer/fonts but the doc still opens in Lib/Mono 10. Why?

I am having similar problem. Have changed default font to Arial 12 but Liberation Mono keeps coming up in part of all of the document despite Arial 12 showing in Tools>Options>Lib writer> Basic fonts Western>Default.
Using Writer on Linux Mint 19