Moto e4 US, please tell me how to fix it

So I have an app called amino, and you can call on it, but I can't without it playing out loud even with headphones in, how do I fix it? It's really annoying and I got this phone to be able to talk to my friends but I can't, I won't be getting a new phone for a few more years and it's really upsetting not being able to talk to anyone #ripmysociallifenow please tell me how to fix it

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