How to switch in Google calendar "event" after it was created?

[AC Question]

In the old Kit Kat version, it was super easy to change the calendar event if it was a work event or an event to share with my wife calendar.
But with the latest Lollipop Google calendar, I can choose which calendar I want when I create an event. But once it's done, I can't go back and change it from work to home calendar. I know it sounds like a stupid question, but I can't change. All my calendars are through a paid Google Gmail account (my own domain name).