Sometimes the use of copy and paste results in loading the document with a heading inappropriate.
We have two way of solving this problem. We may use the button in the image below:

It opens the following window. Use right click and have two options:

Now, use Modify… from the menu and a new dialog window show you.

I change the font from Liberation Sans in URW Chancery L. using the Paragraph Style: Heading 3:

Now the entire document will change automatically.
It is useful when we want to reduce the size of a document.

Another method is to use right click on the text and then modify its properties:

Now the settings window will appear Paragraph Style: Heading 3.
Please make all changes and click Ok button.