Hello jdrescher,
Thanks for reaching out to Apple Support Communities. We've reviewed your question and it looks like you want to know how to adjust app volume on your iPhone. It's understandable that you'd want this clarified, so allow us to assist with that. Please start by taking a look here: Adjust the volume on iPhone. It explains: “When you’re on the phone or listening to songs, movies, or other media on iPhone, you can use the buttons on the side of your device to adjust the audio volume. Otherwise, the buttons control the volume for the ringer, alerts, and other sound effects. You can also use Siri to turn the volume up or down.”
If you have follow-up questions, please let us know. We're here for you. Have a fantastic day!