Before you start
This needs Classes switched on. An admin turns it on in Settings, under Features.
Step 1: Change a weekly class
In the admin menu: Schedule, then Timetable
Click the class on the Timetable, then "Edit weekly class". Change its "Day of Week", "Start Time", "End Time", "Instructor" or "Room", and click "Save Changes".
StudioMomo then asks whether to "Change the whole series" or change it only from the next date onward. Dates students have already booked keep their old details either way.
Step 2: Stop a weekly class
In the admin menu: Schedule, then Timetable
Open "Edit weekly class", switch off "Active" and click "Save Changes". The class leaves your public schedule and shows "Not running" here, and its history stays.
"Delete class" removes the class and every future date, and cancels the reservations on them without telling the students. Stop the class instead unless you are sure.
Step 3: Cover one date with a substitute
In the admin menu: Schedule, then Timetable, then Calendar
The Calendar lists each dated class. Find the date, open its "Actions" menu and choose "Edit session". Pick the substitute as "Instructor" and click "Save changes". Only that date changes; you can also change its times, room, capacity and "Notes on the public schedule".
Dates are listed about a week ahead, so a date further out may not be here yet.
Step 4: Cancel one date
In the admin menu: Schedule, then Timetable, then Calendar
Open the date's "Actions" menu and choose "Cancel session". Type a reason for your staff and click "Cancel session". The date leaves your public schedule, students who reserved get back any class credit it used, and each of them is emailed.
Cancelled by mistake? "Restore session" puts the date back, but the cancelled reservations are not restored.