This is a workbook setting (not an application setting).

Show the File|SaveAs dialog.
Tools|General Options|Uncheck the "Always create backup" box.

Robert wrote:

Excel is appears to be backing up files on it's own. Excel appends the file
name with "Backup of .........xlk" and saves file as an .xlk not a xls file.
How can I turn this off?

--

Dave Peterson