Go to File > Info > Protect Document > Encrypt with Password. Type a password, press OK, type it again and press OK to confirm it. Save the file to make sure the password takes effect.

How to protect an Excel file using a password to prevent unwanted access to your data.

To add a new password, click Protect Sheet or Protect Workbook, type and confirm the new password, and then click OK. To remove a password from the workbook, click Protect Workbook, and then click …

You can add a password to an Excel file to prevent unauthorized users from opening or modifying it.

You can protect the Excel file by specifying two passwords: one to open, and the other to modify. You can later share the appropriate passwords with the team depending on the access they should be …

Add a password to protect your entire workbook and control whether others can open or make changes to it. Protect your file by setting passwords for Open and Modify.

You can add a password so that only authorized users can modify a presentation. Unauthorized users can still open the presentation and then save it by using a different file name.

You can help keep your private notes safe from prying eyes by protecting a OneNote notebook section with a password. When a section is password-protected, all of its pages are locked until you enter …

You can add a password to an Excel file to prevent unauthorized users from opening or modifying it.

Use a password to help protect your Outlook data file (.pst) so that others who share your computer can't access your data.