how can i change settings for internal microphone in iphone 11
What do you want to change? There are not many settings for the microphone. To enable it for certain apps, see https://support.apple.com/guide/iphone/control-access-to-hardware-features-iph168c4bbd5/ios .
If you are having issues with Siri understanding you, you can retrain it:
Retrain Siri with your voice
Go to Settings 
> Siri & Search, turn off Listen for “Hey Siri,” then turn on Listen for “Hey Siri” again.
https://support.apple.com/guide/iphone/change-siri-settings-iphc28624b81/ios
There are 2 microphones on an iPhone 11. There is one on the bottom of the phone to the left of the Lightning jack; the other is on the back next to the camera. The back microphone is used for noise cancellation when on a call and for recording sound with video. There are no controls for the microphones.
is there internal microphone in iphone
