How to create 2nd row from within first row text

Does anyone know how to create a new row from cursor point within an existing row?

Alt-Return

As rogbar said. You can create a line break or split the line by following the faded instructions below the radio boxes. Here’s the preference pane to give context:

Thank you both very much. I didn’t realise that it was within the preferences, and couldn’t find any reference to the subject within the manual.
So simple when you know …