Feedback left ear

Using vivia 7 series. Smart fit software. I’ve tried every size and shape dome there is and the feedback won’t go away. What can I do in detail in smart fit to lessen the feedback. Plus S’s cutout. Sibilance sounds. Thank you. Doug.

It would be helpful if you posted the gain vs frequency chart that includes the feedback curve . Most likely it is happening around 4K

Ok. I will work on that. Thank you.