@michelebolton if it is just the screen that turns black while using it, then check the proximity light sensor. Use the instructions from the [https://www.samsung.com/us/support/answer/ANS10003431/|Samsung site] for that. If that does not resolve it, you may either have a bad sensor or a bad Sensor Flex Cable
If it is an issues with the adaptive brightness thn you go to settings>apps, then enable show system apps then search for a system app named "BrightnessBNR" and then clear that data. To find that system app make sure that you enable " "show system apps"