The list of modules is the place where you select that. I've seen once before that the radio buttons in the first column of that list weren't visible for some reason. Are you seeing radio buttons? If not, try adding the following CSS to your portal stylesheet (in the Site Settings page): .EventsSetting table {width: 100%;} and let me know if that helps at all.
You may need to do a hard refresh (ctrl+F5) on that page to see the new style take effect.
Hope that helps,