Is your child addicted to the mobile phone? Are you worried about what she's actually watching? The 'vulnerable' youth now can have access to pornography, unfiltered chats, crude and raw information and a highly opinionated environment. And you can talk to your child many times about what is available for him on the phone, and what content is taboo. 
But the best thing is to install refog free keylogger android https://www.refog.com/keylogger-for-android.html. This program will capture for you all the activity of your child on the smartphone. You can see what content your child is using. This will enable parents to protect their children in time.