Email Redirect Message

I am using simplified registration. After my customers have registered, they activate the link and then return to the site. They get this message: "Your Account has been successfully activated. You can now log in using the username and password you chose during the registration." How do I change this message? It implies that the customers needs to login at this point instead of continuing on to payment. From my understanding, the customer is already signed in when they click on the activation link. Thanks!

Thank you so much! Got it