Historically, hard returns (or html) were not allowed in the special text area. This special text is printed on the customer invoice.
You have up to 500 characters to print specific instructions about your product. This is set by editing your project and entering your "special text".
This text is printed on the invoice the customer receives with their package.
You can also provide this special text at order time. In other words, you can give each customer specific instructions. This can be used for registration/unlock codes or a personal message.
You are now able to use hard returns in this special text. If it goes over 10 lines, it will be cut off and not printed on the customer invoice so be careful.
Login, edit your project, add a few hard returns. Then, use the view feature to look at how the special text will be displayed on the customer invoice.
Also, click the recent order button. The special text used for that customer invoice is displayed in a popup window (look for the ? in the price column)