Below is a good link video to show how to put on privacy settings.
Please use the timings below to skip to a section relevant to what you need:
0:05 – Facebook privacy
0:54 – Twitter privacy
1:21 – Instagram privacy
1:43 – Parental controls via Windows
2:37 – Parental controls via Apple
Please note: all of the above information was correct as of July 2016. As technology evolves this may differ.