Excel is creating .xlsm backup automatically--why?

I have an .xlsm file that is automatically creating a backup file. I have not had this happen with any other files created. I have looked around looking to find where I may have turned this feature on (unknowingly) but have not found anything. Some clues or hints or rationale.
TIA
Alan

FYI Solution: Need to have file open and click on the Office Button. Save As. In the lower section of the Dialogue box, there is a Tools Option. Click here and when the next dialogue box opens, uncheck the box for always create backup.