Digital Mode setup

I've spent hours trying to get SmartSDR 3.1.12.18 on my 6400M with Windows 10 to connect with MMTTY. All the material I've read or watched either relates to old versions or the process does not proceed as the authors say it should. My goal is to get this running through N1MM although all I've tried so far is MMTTY by itself.

I feel like there is some document I've missed, but so far I'm stymied.

CAT works to PTT and to track freq, and I've gotten it to receive and decode, but never to transmit (beyond putting the rig into transmit mode).

I think I've got the Windows 10 Windows/Settings/Sound set right, but ...

 *  What should the settings be for "Output" and "Input" on Windows 10?

*  Also, what do I do to prevent Windows from reverting to Realtek speakers and microphone every time I close the Settings tab?

When I bring up the SmartSDR DAX panel, it shows the RX stream "1 Slice A" as working (it's blue and and the red bar is fluctuating), but TX Stream will not turn on whether I'm using the my 6400M front panel or from the computer SmartSDR screen even though I have DAX set as "1" in both cases.  The Mic stream on the DAX panel will turn on and stream.  

The IQ stream #1 won’t turn on and says “no panadapter” (although I had it working with some previous setting I can’t seem to duplicate - but even then the transmit audio would not work.

It feels like I’ve used every combination and permutation of settings but get nowhere.

Can someone help