Trouble setting up an alternate host

I am setting up a recurring meeting that I cannot attend every week and that I often will have to leave early. I would like to designate someone as an alternate host so that they can start the meeting and end it as necessary without me being there. I have tried "chat" to get help but nothing there seems to give me the answer I need. Any suggestions? It just keeps telling me that my person is not available to be an alternative at this time.