Hi Nancy,
I’m sorry you are having this problem, let me try to help you with that.
The slug setting only changes the link that you see in the address bar of your browser. It doesn’t influence the page title.
To change the page title you either need to have a modified template file or you need to add some code (a snippet) to your functions.php file. I have a hunch that one of these is the case.
In our knowledge base there is a detailed article on how to change the page title.
https://theeventscalendar.com/knowledgebase/altering-or-removing-titles-on-calendar-views/
Please check it and let me know if this helps in any way.
Cheers,
Andras