Pro Tip: To open formatting options, just select the cell (s) you want to format and press Ctrl-1 (Mac: Command-1). This actually works for anything in Excel: charts elements, images, etc.

While Microsoft Excel automatically reformats time values as hours and minutes, you can manually change the cell's time format to display the seconds as well.

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

Choose Format > Cells > Number tab, and this time click the Special option. Make sure that the Local value is set to English (United States) and you will see four special formats.

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.

However, if you paste a differently formatted date, Excel accepts the source formatting. To further complicate the situation, Excel changes the format of the target cell to that of the pasted value!