Well the truth is I didn't. I just don't go in through Firefox any more, and when I go thru Safari, I choose Google to sign in.
I did look at the fix, but some icons don't seem to appear on the Firefox page on the iPad so I couldn't change things. I just used to get the words 'about blank' in the text box at the top of a completely blank page.
I could do with a one-to-one lesson on a variety of software issues.