Hi Roger!
Thanks for getting in touch!
I’m sorry you are having this issue.
I’m not too familiar with Enfold theme, but let me try and help you out.
Just to confirm, you should be placing the single-event.php and default-template.php template files in /wp-content/themes/your-child-theme/tribe-events/ to make the overrides.
Could you try making the template override in the enfold parent theme and see if the changes apply from there? Perhaps the enfold theme itself is making a template override or customization on its own.
Let me know what you can find.
Thanks,
Victor