How do I update an existing repeating event only for the current event on calendar?

[AC Question]

I have a Samsung galaxy s6 with Android version 5.0.2. I have events which repeat each month on the second Thursday of the month. How can I update the information for just a particular month without changing it for all the events. When I do the update, usually adding a note or location then save, the options I get are: "This and future events" or "all events in series". The option "only this event" is missing. Previously when I tapped an event to edit it, I got the following options: "only this event", "This and future events" and "all events in series". Currently, when I tap the event, these options are not displayed and "only this event" is missing when I do the save.
Can you please tell me how to do an update to only one specific event when your event repeats each month?