Line In being used by another program

I just started to get a flag each time I now try to open a number of programs that use my sound card Line In ,USB. It says that Line In is being used by another program.
as far as I can tell it is not !

My sound settings are correct.

These programs have all worked flawlessly since getting this PC back in 2016.

I tried reloading drivers ,etc. Same flag thing.

This seems to have happened right after I did a Windows 10 version 1903 to 1909 upgrade ,but I am not sure that did it ???
I am unable to rollback to version 1903.

I get sound out of my PC speakers perfect ,even with this problem ,the sound coming from the source I am feeding into Line In, that is to work with the software ,is there . . . but none of the software works anymore because they all say the same Line In is being used by another program and they will not open or work any further.

any ideas ?

Al

I found the problem ,the MICROPHONE setting for APPS had to be ON. I had no idea , but it is obvious when I did the Windows 10 upgrade this additional setting suddenly became important ,when for the past year or so it was not since the MIC was ON but in a different way. Seems there are two MICS ON.
Like many I don't understand Microsoft, since the upgrade suddenly made this an issue. I think these people that upgrade Windows got too much on their plate, they have the customer do the troubleshooting . . . maybe we should get paid by Microsoft too.
I found this fix posted on another site ,regarding this MIC ON for some APPS thing.
I don't understand why some APPS need the MIC on , the APPS I am using never use the MIC ???

Al

I have my system set for "Speakers" (Realtek in my case) as the "Output" device (used to be called Default Audio Playback Device) and Stereo Mix as the "Input" device (used to be called Recording Device).

The last several Win 10 updates change both of these to other devices and I have to manually reset them.