When selecting multiple, e.g. accounts, the Report Designes will create multiple row. Same principle applies for columns.
Sometimes when creating a grouping in a report, the expanding and display blank records options will be greyed out.
This is occurring because the there are no dimensions or attributes in the grouping/sorting tab. This tab must have a dimension or attribute to tell the report which field it should be expanding on.
In the screenshot above, the account field has been pulled into the report and into the filters tab of the group, but not the grouping/sorting tab yet. If we want to expand on account, then we would drag and drop that dimension into the grouping/sorting tab, close the Layout editor to refresh the settings, then reopen the Layout Editor and select the expanding box.
BI360 Report Designer 4.x and 5.x