Please check the following points: 1) Make sure all input and output cables are correctly connected 2) Make sure the mic input is clear and in well-order 3) Check your device to see whether it is in good condition 4) Make sure the volume isn't at the min. level  If the issue still exists, please try to restart your device.

Of course, the headband of the gaming headphone is made from high-quality stainless steel. Simply adjust them by straightly bending out these headphones. 

You can turn off the microphone by the "microphone on/off" button during a call when using the headphone with a mobile phone, but cannot do that when using it with a computer via Bluetooth, because the Bluetooth protocol of computers is different from that of mobile phones.