How to make the path respect the rounded corners of my triangle?

Question

Forgive me if I'm using some of these terms incorrectly but I am following a tutorial on this video: https://youtu.be/W-p3MojvdBA?t=2m41s.

I created a rounded triangle but the actual path still looks like a triangle with sharp edges, which complicates the next step in the video. The guy who made the video suggests going to the pathfinder and clicking unite with the dark triangle selected, but when I do this, nothing happens. On his video when he clicks this button, it unites the blue outline (what I think is the path?) to the rounded corners of the dark triangle.

Answer 1

The tutorial creates the rounded corners with the corner widget that creates Live corners. Using Pathfinder on a shape with Live Corners will expand those corners...

Your shape has rounded corners created with "Round Corners" effect, which is a completely different thing. To expand the rounded corners created with an effect you simply need to expand the shape's appearance by going to:

Object → Expand Appearance.

Live corners are a new feature of CC and not available in CS6 (which it looks like you're using), so you'll have to stick with the effect (and expanding appearance).