If you find out there are changes that need to be made to an already scheduled event, Otus makes it simple and straightforward to edit events within the calendar.
Select Calendar from the home screen.
To edit a scheduled event from the To Do List view, select the ellipsis to the right of the event and click edit.
You can also edit an event from the Calendar View. Select the desired event and click the pencil in the upper right hand corner of the popup.
Change the event details and then click the save.