When the linebreak property is on 'auto', the line break is automatically done when the text reach the end of the line.
When it's on 'manual', there's no line breaks till then you press 'enter' key.
In all case, if you want to make a line break, press basically on 'enter'
Finally, if you want to make a line break in the 'set text' action, use 'shif'+'enter'.
Hopefully it helps you.