Using iPad audio when connected to an external screen

Hello beautiful community,

So am using an ipad pro 11 inch and I work with a lot of ppt presentations. So i bought a usb c hub which gives me HDMI, VGA, ethernet, usb 3 and 3.5mm audio. When i connect my ipad to the hub, or to the HDMI cable - i have the official Apple adapter as well - the audio control from my ipad becomes disabled, and the sound is automatically routed to the projector sound output which is usually very low. So what can i do to control the audio volume from ipad when connected to the hub or to the hdmi cable or the VGA as well ???

really appreciate your support with that.

Thanks.