Always protect any important and sensitive files with a password before storing or emailing them.
To do this for Microsoft applications, go to File, Information and then click Protect Document, as shown below.
Then select Encrypt with Password, this brings up the option to add a password, as shown below.
If you are sending the document to someone, remember to send the password to the recipient by means other than email – options include over the phone or via text.
Read our further guidance about Protect Data.