New
#11
I'm not sure this will help but it is all I have at the moment.
Open the Sound window as below click the Properties button (1).
In the right side of the pic where marked (2) it should show mic inputs. As you can see on mine the rear is enabled.
If the apply button is not greyed out as in my Snip then highlight the jack you wish to use if more than one is shown then click "Apply" then "Okay".
This may be of no help but I provided what I could find.
Mike