Wow, I didn't think anybody used tree view any more.... I think you can set it to show all replies and still use tree view, but you'll probably like linear view better if you try it. Go to your User Control Panel, Edit Options, and scroll down to Thread Display Options. You could just change Number of Posts to Show Per Page but I suggest you try linear view -- change Thread Display Mode to Linear - Oldest First. Then scroll to the bottom and click the Save Changes button.
Linear mode shows all posts in a thread on the same page, starting with the first post and showing the others in chronological order after it. If it's a long thread it will be several pages, but still in chronological order.
You might find it a little confusing just at first, but once you get used to it you'll almost certainly prefer it -- just about everybody does. vBulletin only preserves other views for people who are used to the old way some early forum software worked and don't want to try anything new.
