By default, short dates in Excel are formatted using slashes (3/14/2016). If you use a lot of dates in your worksheets, and you prefer to put periods in your dates (3.14.2016), you can easily change the format.
First, select the cells containing the dates you want to change. Then, right-click on the selected cells and select “Format Cells” from the popup menu.
On the Format Cells dialog box, make sure the “Number” tab is active. Then, select “Custom” in the Category list box.
Enter “m.d.yyyy” (without the quotes) in the “Type” edit box and click “OK”. To use a two-digit year in the dates, enter “m.d.yy”. Entering “mm.dd.yyyy” inserts a leading zero before single digit months and days and uses a four-digit date (01.04.2016).
The dates now use periods instead of slashes.
You can change the date format back to slashes or to any other date format, such as a long date or a date and time combination, using the same procedure. Just select “Date” in the Category list on the Format Cells dialog box and select a format in the “Type” list box.