In-Call to homescreen Setting help

[Fanilow33]

Hi there. i am new to the iPhone and was converted over from a droid. my issue is that when I am in a phone call after about 5-10 seconds my phone will go to the homescreen rather than stay on the call screen. Is there anyway to change this? I have try to look online but couldn't find anything nor in the settings under phone. Please help. Thanks so much.