Hi Jan,
Thanks for getting in touch and for including a screenshot- that really helped me understand the issue right away.
The @ sign is not replacing the year, it’s just that on the single event page and in List View the date shows as Month Day @ Time. The year only shows if it is not the current year (that is, events in 2015 would show the year but not in 2014). This is not controlled by the WP General settings or changeable via the translation, but it is possible to change it with some customizations of the calendar plugin.
If you’d like some help changing the date format or the @ symbol, please post a thread in our Events Calendar PRO Forum and a member of our support team will be able to help you there. Thank you for your support!
Best,
Leah