If you see it listed as macro it must not be in the right spot because it should show up as FormatNumberString.

Complete these steps.
1. open your workbook (until you are comfortable editing in the VBA editor you should only have 1 workbook open)
2. Press Alt + F11 to open up the editor.
3. On the Menu click Insert>Module
4. In the new module that comes up, copy and paste the entire code from Option Explicit to End Sub
5. Close the VBA editor or run the code from the editor by pressing the play button while your text cursor is somewhere in the code. Again be sure your workbook is backed up before running because you cannot undo a macro.

Let me know if you have any questions.

Thanks