Hello @Marymegs,
Welcome to the Zoom Community! We're glad to have you here.
Kindly check if you have cleared the prerequisites for assigning an alternative host:
Prerequisites for designating an alternative host
- Zoom desktop client for Windows, macOS, or Linux: Global minimum version or higher
- Zoom mobile app for Android or iOS: Global minimum version or higher
- Both users need to be Licensed and on the same account
- For webinar, the user who schedules the meeting needs both a license and the webinar add-on; the alternative host only needs to be Licensed
- Alternative hosts must be signed in to Zoom with the correct account in order to be granted the host or co-host permissions
You can read more in this article.
Please let me know if you need further assistance.