Frequently Asked Question

To prevent others from accessing data in your Excel files, protect your Excel file with a password.

Note: This topic covers file-level protection only, and not workbook or worksheet protection

1. Select File > Info.
2. Select the Protect Workbook box and choose Encrypt with Password.
3. Enter a password in the Password box, and then select OK.
4. Confirm the password in the Reenter Password box, and then select OK.

https://support.microsoft.com/en-us/office/protect-an-excel-file-7359d4ae-7213-4ac2-b058-f75e9311b599#:~:text=Select%20File%20%3E%20Info.,box%2C%20and%20then%20select%20OK.