Please Change "Groups" to "Please Login"

I thought that someone had given me code for functions.php to do this but I can't find it anywhere in my tickets.

When we are notified by email of a topic in the forums we get a link - example but when I click on the link I get a page that says "Groups". I assume this is because I am not logged in and wouldn't mean anything to any of my members. Can you please tell me how to change that default "Groups" page to read "Please Login" instead of "Groups". Thank you.