Hi Tina,
I have figured this issue out and wanted to share so that it can help others who may not know this either. :)
- Expand the grouped rows in your spreadsheet.
- Select the section of rows and go to the Data tab and then in the Outline/Group section select the arrow in the bottom right box to open Settings. By default, both "Directions" are checked. Uncheck the top box "Summary rows below detail" and it will make the + sign line up with the heading row.