GarageBand: no way to change microphone input level on iPad pro

On my husband's iPad Air2, GarageBand allows you to change the input level of your voice on the microphone input.

On my iPad Pro this is not possible and the Input Options on the Audio Recorder offer a different set of options.

It is really difficult to get anything like a decent sound level even when shouting! I have used the track volume settings to reduce sound from all the other instrument, but this seems a poor quality work around.

Does anyone have any ideas?

Many thanks!