If I want to find all the posts by a certain poster in a thread, how would I go about that?
Thank you
Open the thread and go to the first post. At the bottom will be a list of people who’ve posted to the thread. Click on whoever is the target of your search.
That will bring up the user’s “card.” There should be a x Posts in topic button. Click it to see all of their posts in that thread.
I think this second reply will add the button to my card.
Not if it’s in succession apparently. Try it now.
You can see it better in long, well populated threads. Try the Pro-life/pro-choice thread. Under the OP, there will be a short list of avatars. Click the down arrow to expand it.
There are some requirements for being listed there. I think that you have to have at least two posts in the thread, for instance.
If the person you’re looking for isn’t there (or if they don’t have a button), click the search icon, make sure that search this topic is checked, and type in their username (don’t forget underscores).
Got it, guys. Thanks!
Another method, use the search feature. Click on the magnifying glass icon, check ‘search this thread’ and then enter the user name in the box.
Ctrl-F can also work. I prefer keyboard shortcuts when available. 
Enter the username in the @XXXXXXXX form to find the posts they’ve made, and not include other references to them. And it’s “Search this topic”, not thread.
I stand corrected.
It’s not necessary to go to the list under the first post.
Click on any avatar anywhere in the thread, and you’ll get ‘x posts in topic’ if there’s more than one.
Click on that button to filter the topic and see only their posts. Very useful.