How to customize the toolbars in LibreOffice Writer?

1º We are going to add Superscript and Subscript, so, go to "View", click on " Toolbar" and go to "Customize".

2º Now go to "Toolbars", select "Formatting" in "Toolbar" and select Superscript and Subscript.Here if you press OK these tools will be added but, we are going to add a Manual Page Break so click on "Add"...

  
3º Select " Insert" in Category and "Manual Page Break" in Commands. Press Add and OK...

4º Now select the tool that you want to change it icon...and click
Modify\Change Icon...

5º Select the new icon or import it.Click OK.

6º As you can see, the icon is changed.Press OK to finish.