How do I print a copy of a returned for with multiple line boxes so that all of the content displays at once?
If you go to the "Response" tab and select the response you want to print you can "Download Response as PDF Form" from the dropdown at the beginning of the table row, or "Download Selected Response as PDF Form" from the File dropdown menu.
The PDF will have the entire text and you can print the PDF.
How do the respondents print a copy of the form with multiple line boxes so that all of the content is displayed at once?
You can enable Email Receipts and choose to include the form data, this will email them a confirmation email including the data in a text list (it will not look like the original form).
If they need the original form format to print you could email them the PDF that you download from the Response tab.