...that when topics look really funny with a top post and a funny outline type tree thing below, you have probably accidentally changed your display mode. Other people have done it too. It happens.
Go to a topic and look up in the dark blue bar where the topic title is on the left - on the right there is an OPTIONS button. Click the arrow to get the dropdown menu. You will see DISPLAY MODE. Click on > SWITCH TO: STANDARD. That should make it look the way you want and there you go.