Thank you for your input. I checked Settings/Appearance; the font is medium and set to standard. I am unable to reset the Theme to default. Once I click on Theme, a whole list of themes appears, but I don't see any default.
On another note, once I click on the three dots at the upper right, the list that comes up (New tab, New window, New Incognito window, etc,) is now also double spaced. I guess I have to live with it, but it is annoying. I will try to make a System Restore to a point a couple of months and see what happens.