Font changes for no reason

I am running into an issue where the font switched from Optima to Lucinda Grande for no reason, other than I might have backspaced or something. Is there a fix for this?

Try not to hold the shift key down while hitting return - a good habit to break as it creates a soft return in Word and other word processors too. Full explanation in the thread on this exact same topic here:

https://forum.literatureandlatte.com/t/font-keeps-changing/6736/1