Speakerphone mic does not work how do I change to main mic

My mic when using speakerphone does not work but mic works fine in normal call. I tested it with factory test via oneplus support so for sure the secondary mic( the one at the top) does not work. How do I edit mixer_paths.xml to only use main mic for speakerphone and anything else that might use Secondary mic. Secondary mic is on the cpu board so not easy/cheap replacement like the main mic. I'm using rooted Oos 3.0.2 Marshmallow oneplus 2. I tried opening up mixer_paths.xml and played around but I'm really just guessing, don't really know what it all means. Anyone know exactly what I should change to make this happen or any advice to narrow down my playing around would be appreciated. Ty

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