If you often wrote or have lots of top secret company documents made with Microsoft Office suites (Word, Excel, PowerPoint) you may feel want to secure those documents, so those documents can only be seen by authorized personnel. You can do this by adding password to your documents.
Here are some steps you can do to add password to you office documents:
Open your Word, Excel or PowerPoint documents, click the Tools -> Option menu, then select the “Security” tab.
Just type the password you wish in the “Password to open:” column, after that click on the “Advance” button to choose the encryption type, just choose the one you prefer, click OK button twice to save the changes.