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

Excel spreadsheets permit you to stay organized while managing large amounts of data, which can be organized in a number of ways. One popular way to organize this data is by date. Excel has a default ...

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.

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.