Good evening Peter and welcome back!
Thank you for reaching out to us.
I would love to help you with this topic.
How do I change the size of the font of the main title on a mobile device?
In order to gain full power on your site’s look and feel, I would highly recommend reading the following article: https://theeventscalendar.com/knowledgebase/using-google-chrome-developer-tools/
To have different display rules for mobile, you will need to use @media CSS rules. Here is a pretty nice article on this topic: https://www.smashingmagazine.com/2010/07/how-to-use-css3-media-queries-to-create-a-mobile-version-of-your-website/
In short, this will let you have different font sizes for mobile (among other things).
Could you please provide us with your complete system information in a private reply using the instructions found in the following link?
https://theeventscalendar.com/knowledgebase/sharing-sys-info/
This way I could give you an example of what that means.
Let me know how that goes.
Best regards,
Geoff B.