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

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.

How to Auto-Format the Date in MS Excel. When you create Microsoft Excel spreadsheets that contain one or more columns of dates, you can make things a bit easier if you pre-format your cells to ...