To display more than one line of text for a Text field, navigate to the Question Configuration Panel by selecting on the question field. Then toggle on "Allow multiple lines of text" and set the number of lines desired under "How many lines of text should the question be?".

Gotchas
- This won't stop people from entering more or fewer lines of text. It will only change the default size of the text box that is displayed.
- Long text fields aren't a different field type - make sure to start with a standard "Text" field, and proceed to update the configuration options.