Select the cells containing the dates
Right-click and choose Format Cells
Go to the Number tab
Select Date
Choose a date format from the list
Click OK
To use a custom format, select Custom
Enter the desired date format code
Click OK
To change the date format on the ribbon, go to Home
In the Number group, open the format drop-down
Choose Short Date, Long Date, or More Number Formats
If the date does not change correctly, check whether the cells are stored as text
Convert text dates to real dates before formatting