I’ve never liked Excel’s default setting for its outline button structure. If you notice from the example below, the default setting puts the outline button below your summary rows.
Visually, I don’t think this is intuitive. I prefer to see the outline button above the summary rows. Making this change is very simple. First look for the Outline menu in the Data tab of the ribbon. Click its expand button in the lower right corner to see the full menu.
Once you are in the menu, uncheck the box for “Summary rows below detail” and click OK.
Now the outline button will be above your summary rows. Done.