A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Hello !
This is a known limitation in Microsoft Excel, not a formatting mistake.
Excel does not store dates earlier than January 1st, 1900 as real date values.
You'll need to store your date as a text, or split year/month/day by creating three different columns.
Once you have your three different columns, you can use the text formula and the & symbol to join the text together.
Please let me know if you have any other question !