It looks like your set the editor breakMode to UseBROnCarriageReturn.

 

So when you use the ENTER key while typing, the break tag <br> is used to force the browser to start a new line instead of a new paragraph  or a new division.

 

All the contents you are editing are included in a whole paragraph.

 

When you use the indent/outdent functions, the whole content will move together. That's the drawback for using <br> tag.