How do I edit the template for the Zoom Events 'Verification code' email?

Hello all, 

I'm setting up my first event in 'Zoom Events'. I can see in Communications / Emails how to edit the templates for many emails, but not the one a delegate receives when starting the process of registering via email (not with a Zoom account). I asked Zoom support via chat but they couldn't solve it and said they would raise a ticket!

Main issue for me is that the current style has white text on a white background, so I'm having to change them all. Second question - is it possible to apply a global change to the style of all email templates? This was what I thought might happen when I saw 'Global styling' but seemingly not as it only updates the single email template I'm in.

Any tips gratefully received - many thanks, Chris