Your internet browser has a memory, called the cache.
Since most websites do not change, your browser
actually shows you the website from its memory
from the last time that you visited the website.
That's a problem for viewing message boards
because the website keeps changing with new posts.
Try using your refresh/reload button. This will cause
your browser to go get a new copy of the website.
Try a "Control + Refresh". That works to force both the
computer and the ISP server to refresh the whole page.
You can also learn to change the settings on your
browser so that it always gets a new copy.