So you have an Excel workbook that contains confidential information. You want to prevent unauthorised access to the file. One way is to assign a password to the file. When anyone tries to open the file, they are asked for the password:
Warning! There are many “password crackers” available via the Internet. Setting a password on a file is more of a deterrent. If someone is determined to break in to the file, they probably will.
Select File > Passwords
Create the password that must be entered by anyone who wants to open the file by typing it into the “Password to open” field (note – passwords are case-sensitive) and click OK
Re-enter the password and click OK
If you set the view in Finder to display icons, a password-protected document displays with a padlock on it:
Opening The File
Double-click the document icon (or select File > Open in Excel). A dialog box is displayed, requesting the password.
Type in the password and click OK
Removing the Password
Open the file
Select File > Passwords
Delete the asterisks (that represent the password) from the Password to Open field
Click OK
Save the file