Hello Thuy,

Thank you for purchasing our product, and for reaching out to us.

For specific information related to events, custom fields will be shown in the same place on the front-end booking form like for the appointments, but when it is about the back-end the place for the custom fields is different and you will find them when you open the Attendees list and click on any attendee. Once you click on the attendee on the list you will see an option “Edit attendee” and by clicking on that option the custom fields will show up.

You can see more about event custom fields in this short video:

But unfortunately, when you create a new different event you need to add custom fields manually.

I'll kindly ask you to add it as a feature suggestion on this page. 

Features are pushed up on our "to-do" list when there are a lot of customers requesting those features, so having your vote as a customer can be beneficial to this feature being developed sooner.