Please keep in mind that there is a difference between the Home page activity view, which shows all recent activity -- regardless of whether you are caught up, but threads with new content will be bolded -- and the 'What's New" page, which will only show threads with new content (those you are caught up on will vanish from view when the page is reloaded by clicking the "What's New" tab again). These are two different types of views and different individuals tend to prefer one or the other view so both exist so that everyone may use whichever view they most prefer.
The behaviour you all all are desiring will be found under the "What's New" tab on the main menu bar. Others prefer the Home view because caught up threads do not magically disappear from view (which seems to aggravate many when they wish to return to a recently visited thread that has vanished from view), but we make both alternatives available to everyone...just select based upon personal tastes.
While we are experiencing some other site related issues with (mostly) certain desktop web browsers due to some mixed content issues due to SSL changes that were made (and I still do not know the Why of those changes, I'm still awaiting an explanation as I do not want to just back out other's changes without knowing what the intent was) these two views should be working as expected for all users provided you are logged into the site at the time (otherwise the "Home" page view is generally more consistent in behavior for both logged in and guest members since past activity information is not preserved for guest/unauthenticated visitors).
