Perhaps you are referring to the "New Content" feature? The "New Content" button is a quick way to see topics which has one or more new posts since you last viewed the topic. It is not possible to start a new topic from there.
Even though I've been a member a while, I haven't been really active until this year, reading more than I post. I now read and search here daily. There is a learning curve. It's like buying a new cell phone. You have to learn how everything works. I recently figured out that the "new content" button doesn't bring up all new content. I would go days thinking no one posted anything anywhere. Then, I figured out if I hit the forum button, I could see all the new content. Does the new content button only work for threads you have started or commented on? Yes, for those wondering, I am blonde.
On the left side it says Time Period. I use past 24 hours, but there are several time options. Choose the one you like. You can change it at will.
Thanks, Lou. You beat me to it. I have always had mine set for "Content I have not read". If no results are being received, it may be that one of the options in the Other section at the bottom has been selected.