How to change the user's email address?
It is not possible to change the user's email address. If the email address needs to be updated, you can create a new profile and deactivate the older one.
Why I am getting the error while uploading users?
You may be getting upload errors for a variety of reasons. You will receive an email containing a file explaining the error in each row.
Why an event instance is not visible to the users?
The user may not be able to see the event instance because of mapping between user role and the access. The instance will be hidden if the access is Semi Private or Private for a user role.