Hi KellUD1,
Please check the following:
1- Make sure that you are in design mode and not in preview mode. To see that you have 2 options:
Option 1: In the InfoPath title bar, you can see whether you are in (Design) or (Preview) mode.
Option 2: Right Click on the xsn file and choose "Design" from the menu.
2- Open the File menu. The "Save as Source Files" option should be underneath the "Save As" option.
Kind Regards,
Samir