Open the Word document
Click File
Click Info
Click Protect Document
Choose Encrypt with Password
Enter a password
Re-enter the password to confirm
Click OK
Save the document
Close and reopen the file to verify the lock
Open the Word document
Click File
Click Info
Click Protect Document
Choose Encrypt with Password
Enter a password
Re-enter the password to confirm
Click OK
Save the document
Close and reopen the file to verify the lock