As a Network Creator, you can control the comment order on your Ning Network. By default, oldest comments appear first on blogs; on every other type of content, the newest comments appear first.
If you want to modify the order of comments on your Ning Network, just head to the My Network page and click on “Features” in the Settings area. Toward the bottom of the page, under “Change order,” you have the ability to change the ordering for comments on My Pages. You can also choose the order of comments on each feature individually for all of your Ning Network’s features except the Forum.