Numbers: How do I make it display the full year
I have a Numbers spreadsheet that shows the date as 5/6/21, but I want it to display the dates as 5/6/2021, the full year. How do I do that?
Select the cell(s) you wish to format and open the Format sidebar > Cell section. Here, choose "Date & Time" and configure the Date entry to an option with full years.
Read more in this Apple Support document: https://support.apple.com/guide/numbers/format-dates-currency-and-more-tan23393f3a/mac