Hi Shannon!
To remove the dirt from the small ports on the phone, I’d recommend using a can of compressed air or “dust-off” to blow away any dirt, debris or dust inside. Additionally, you can try using a Q-tip dipped in a little rubbing alcohol (Isopropyl alcohol) to help clean the ports out, but you may have to pinch or flatten the Q-tip’s cotton so that it fits inside the ports.
I’m not too sure what to suggest regarding the volume booster app you’ve installed, unfortunately.
I hope this helps!