increase microphone volume iPhone 6s
How can I turn up the volume in the microphone in my iPhone 6s. I have problems with people not being able to hear me properly, mainly one elderly relative but she can hear me fine on the landline, others hear me but softer. Is there a way to increase the microphone volume? I have a brand new iPhone 6s from an Apple Store in Brisbane. Has anyone else had this problem? thanks
iPhone 6s, iOS 11.1