Quick event manager.

Hello, please help.
I have just upgraded to the newest version, however whenever I click, “registration form” settings within the front page of the event I am editing, I get this message on a new page, “Sorry, you are not allowed to access this page”.
I have tried to go back to a previous version, but to be honest have no idea how this can be done. I have opted in as requested, but that has made no difference at all.
Please can you give me a solution to this as soon as possible.

Thank you,

Richard Grant, K9 Help. richard@k9help.net http://www.k9help.net