Good evening Donna and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
I would love to help you with this topic.
As a first step, 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/
Normally, there should simply be a Cost field that appears as part of the Event section (not the ticket section). Whatever value is entered there should now appear as a cost everywhere but in the ticket detail section.
You can also accomplish this via a snippet.
You could apply the following snippet in the functions.php file of your theme (without the PHP tag at the top): https://gist.github.com/GeoffEW/69f8a033fb614c78b3de45a197431135
But first to be extra safe, before making any changes to your functions.php file, you should make a backup of that file.
Let me know how that goes.
Best regards,
Geoff B.