Do you think a ten year old (5th grade) should have an instagram?

[426]

I'm a 16 year old in high school and about 2 weeks ago I got an instagram.I was showing my little sister,who is ten and in 5th grade,the pictures I posted on it and she thought it was really cool.She has a smart phone and I told her that she shouldn't get an instagram because she is too young.

Yesterday I came home from being gone for the weekend and found out that she has had an instagram for about 2 weeks.On her instagram she has about 100 pictures.About half of them are of her.This angers me because she is 10 years old and is posting pictures of herself online.In one of the pictures of herself she zooms into her shirt that clearly shows what school she goes to.I told her it's not safe to do that,but she told me to mind my own business.Some other pictures she has are pictures that she shouldn't even have on there or see.They include a cartoon of a deer with an eye patch being shot in the head,an anime girl in revealing clothes,pictures that say to follow her,and some she doesn't even understand.I looked at the people she follows and most are people who have zero photos and she doesn't know them.One of the pages she follows is the movie Ted's page.The movie is R rated and she shouldn't even be looking at the stuff that gets posted on that page.

I've told my dad and asked him if he wanted to see the things my sister has been posting on instagram,but he told me to leave her alone.I told my sister to delete some of the inappropriate photos,but she didn't listen,so I started to leave comments on the photos telling her to delete them and warning her.She ended up crying to my dad and my dad threatened to take away my phone and told me to stay off instagram completely or he would delete it off my phone.On my instagram I have 10 photos and my profile is private.I went to my mom to try and talk to her about what my sister has been posting,but she yelled at me about how I shouldn't worry about my sister.Then she asked my sister for her phone and went on my sister's instagram.My mom ended up blocking me from my sister's page so I now I can't see her photos.

I feel that this is totally unsafe and that my parents aren't taking strong enough measures to keep my sister safe online.I want to show my sister an online safety video and so far I've found this one:https://www.youtube.com/watch?v=_o8auwnJtqE

What should I do about keeping my sister safe and how can I get it through my parent's heads that my sister isn't being safe online?Also are there any other safety videos I can show my sister that are appropriate for a 5th grader?
@Cynical_Student I guess you didn't read the whole thing,I'm talking about my sister.I'm only 16.