Bob P -
This is an interesting question. Unfortunately, I have some suggestions to help you, but not the exact functionality you are requesting.
When you are on the main page (forums.ni.com) you can see how many new messages are in each board. And, when you are on a board page, you can see how many new messages are in each thread. From this page, if you click on the number in the NEW column, you are taken straight to the new messages in the thread. But, this doesn't answer the question of how to find those threads that have been updated in the first place.
In your profile, you can determine how many threads you would like to view per board page, so you can increase the number so that you don't have to scroll through so many pages to find the new topics. I looked to see if there was a way that you could change the order of the threads in the board view to sort them by last update date rather than creation date so that the new threads would show up at the top of the list, but I didn't see that option.
I will submit this as a feature request, and hopefully it will be something that we can add to the community moving forward.
Thanks for the feedback,
Molly K.
Web Support & Operations Manager
National Instruments