Freddy, basically I don't think you can do what you are asking for, "Show new replies to your posts" will always list all posts that you have made a comment on, you have asked the system to show you ALL threads that you commented on that have new replies so whether you are interested in that one or not it will always show those that have new posts added.
This is the same for "Show unread posts since last visit", this will show ALL threads with new posts, post updates since your last login.
As I understand it the way to view ONLY the posts you have an interest in is to choose the notify option and respond to the email notifications you receive, when you are not interested in that post then choose unnotify and you won't receive email notification.
The two options above will show you all threads that have new posts on them.
That is how I understand it to work.