The new Google Sheets is now the default option
Back in December we announced the launch of the new Google Sheets. This new version is faster and can support larger spreadsheets. Over the next couple of weeks, rapid release domain users will automatically be upgraded to the new Sheets. Spreadsheets created after the upgrade will use the new version. Users may opt-out of this experience through the settings menu in Sheets.
The new Sheets will be available to Schedule release domains in the next four to six weeks.
Google Apps for Business, Education and Government
Reference by : http://www.google.com/