Could you describe a little more what happens? - like what kind of navigation you are doing?
When I just browse around the family tree from profile to profile or from profile to family tree or descendant view I stay in the same window, same tab, unless I specifically choose to have a new tab or new window (by one of the right-click options). If this is the kind of navigation you are doing it may have to do with your browser settings or the device you are using.
When you are creating new profiles as relations to existing ones from the edit view you WILL get new windows/tabs, and yes, this can get confusing.