How to: Make a backup copy of document.
Solution:
Select the 'Always Create Backup Copy' check box on the 'Save' tab.
1) Select the 'Tools' menu and select 'Options...'. (The Options dialog box appears.)
2) Click the 'Save' tab.
3) Select the 'Always Create Backup Copy' check box.
Always Create Backup
4) Click 'OK'.
NOTE: When this feature is enabled, with each save Word renames the previously saved version of document as 'Backup of Document Name.wbk' (where 'Document Name' is the name of the saved file).