How to Expand & Collapse parts of a Word 2013 document

The default setting seems not to work in newer versions.

I was just lloking for a way to remove this blue grey triangle. Now after watching your video, I realized that I just have to select the text and then select the Heading as Normal.
Your video helped me a lot. I was getting frustrated by this problem. Thank you very much.

Simple clear and solid information, better than Microsoft itself explanation

That was explained in a simple, lucid and easy way, thanks

? Is this feature available in 2010 or I should buy 2013

great function that we don't have it on the stupid MAC

Thank you so much. That just saved me many, many hours of learning Visual Basic.

Very clear and simple. Thanks

Thanks so much, helped me to quickly look through the topics of my long article.

Thank you straight forward and easy to understand

thank you for your effort,
I used heading style and I want to be collapsed by default when I open the document, when a went to setting shown in video, the option was gray indicating that I can't do it. 
is it problem of format style ? or what ?

Thanks mate! This was super quick and super duper useful!

How do I delete this. I don't need in my document, how do I remove it?