Encrypt an Excel file with a password so that it requires a password to open it.
1. Open a workbook.
2. On the green File tab, click Save As.
3. Click on the Tools button and click General Options.
4. In the Password to open box, enter a password and click OK.
5. Reenter the password and click OK.
Note: this feature also encrypts your Excel file. If you lose or forget the password, it cannot be recovered.
6. Enter a file name and click Save.
It requires a password to open this Excel file now. The password for the downloadable Excel file is "easy".