iPhone stuck in phone mode.

I need some insight! My iPhone will get stuck in phone mode, and i can't get out of it. This happened to my old iphone as well - but I just brought that one to the store and exchanged for this new one because the old one had water damage. This one - I got it yesterday. I will hit the home button from texting, and it will go straight to phone mode, and will not return to the home screen when I hit the home button. Anyone else have this problem? I need some help!

Thank you 🙂