Hello.
I would like to know why the option to expand/collapse disappear when I add a bookmark to a title?
Example:

I write a common title


So I set a heading style to it


By clicking with the right mouse button it is possible to see the option to expand/collapse


So I add a numbering and the option disappears




I use office-pt-2013
Anybody know whats happening?

It does not happen in my version of Word 2013. I followed your steps.

I would urge you to not use that numbering button but to rather attach the numbering to your heading style using the procedures set forth in How to create numbered headings or outline numbering in Ribbon Versions of Word by Shauna Kelly. I do not know that this will change your outcome, but do know it will make your numbering more stable.

Attached Images

00 deleteme 0.png (35.1 KB, 14 views)

I know what I did, I changed the title style. :/
is not possible to create a style and keep the menu expand/collapse?

The style must have an outline level to show up in the expand/collapse scheme of things. The built-in Title style and the Heading 1 style both have outline levels of 1. You can create a custom style that has an outline level as well, but must do it actively.

Why use Microsoft Word’s built-in heading styles? by Shauna Kelly