How should an Excel file be formatted so that there will be multiple lines in the description instead of the description wrapping when imported into QuickBooks Online?
In the Excel file, enter the full description in the cell. Then, place the cursor right before the first character that needs to appear on a new line and select the ALT and ENTER keys on the keyboard.
Below is a screenshot showing an example of this technique. Please note that the example shown is for QuickBooks Online, but this also works when importing into QuickBooks Desktop.
Sample Import File
Invoice in QuickBooks Online