How can I prevent easy screen burn-in?

When aim talking fast, I'm talking 10 minutes on around 3/10 brightness on my iPhone 6S LCD screen. I was just playing Fun Run and the control buttons had a ghost image on the screen after TEN MINUTES! Anybody have any solutions? Do I just need to replace the screen?

Added (1). Note: This has never occurred before today, and my lighting hasn't changed from the norm.

Cccgg vgg vggg cvv

LCD screens don't get screen burn in, only OLED screens do, and not after only 10 minutes. Sounds like a glitch in either the app or iOS.