Anonymous submissions – change message

Hi,

I don’t want people to submit events without logging in, but I would like to change the message when they try to. Right now it says:
“Unauthorized Access
You do not have the rights to manage this Event.”

This doesn’t give much information and it sounds more like an internal error to whoever sees it.

I would like to change it to something more:
“You need to login or register in order to submit events. Click here”

I can’t seem to find the file or settings panel that lets me do that.

Any help, please?
Thank you

The page I need help with: [log in to see the link]