Open the Excel 2010 file that you want to make format changes to. Select the top-left cell in the range of cells that you want to change to the accounting format.

It's easy to change the date format in Microsoft Excel. You just need to use the "Date" drop-down menu, which gives you plenty of options.

You can change the date & time format in Google Sheets & Excel Online using this guide. Use different date & time formats in spreadsheets.