You mention a couple of different issues actually so I’ll try to get them one at a time - I use the jabras, like them quite a lot, and know some of the issues you are having.
Re the feedback - when you are fitting you will see a button on the bottom, towards the left, that says calibrate dfs. Sit in a quiet room and run it. That is how it adjusts the feedback.
Re the m&rie vs not. I have my all around program set to m&rie (it’s in the fitting advanced section I believe - not sitting at my computer ;). It is by default on all around. Using the default uses the mics on the behind the ear (bte) piece and occasionally the m&rie. The m&rie setting uses primarily the m&rie and makes for exceptional wind noise reduction. However, watch the results in the calibration as if it goes too far into the gain levels it’ll stop being as effective. I know this is a long thread but lots of good stuff on the jabra and m&rie.
Re the streaming audio - when you stream it turns off the m&rie and goes to the mics in the bte. In the settings by default it lowers the mics when using them. I changed it to stay the same, but that’s a personal preference.
Re turning the m&rie off - the normal setting doesn’t use the m&rie much but I don’t know of a setting to turn it off.
Good luck!