Help? My Little Sister Is So Tiring

I 15f have a little sister who is 7 and she constantly hits, pulls hair, kicks, doesn’t listen, and yells. I’m so incredibly tired I really don’t know what to do. There have been so many instances where she has gotten super angry for the smallest things and my parents don’t really know what to do either. I think it may be because of her screen time and all the crap she watches on YouTube but whenever I try and tell that to my parents thy don’t set limits at all. Sometimes I try and get her to not watch brainrot on YouTube and ask her if she wants to watch a Disney movie and color or something but she usually yells at me to give her the remote or say “I don’t like movies they’re too long.” I’m worried about her attention span and how much it’s affecting her. Sometimes, however, she is a complete angel, she’ll cuddle with me and watch movies and talk to me about things on her mind but that can change in a millisecond. If I accidentally interrupt her she’ll go ballistic and get extremely mad which will most likely result in hitting, hair pulling, and kicking. Whenever I try to protect myself by shielding where she’s hitting or holding my hands out when she’s charging at me as to not get hurt, she will just get more mad and will say I’m hitting her back. Parents of Reddit, what do I do? She doesn’t use her words to communicate her feelings at all, which I’m not expecting her to just automatically know since it is taught, but is it too late? She’s in therapy like myself which sorta helps but not really. If I try to have any sort of conversation with her about her behavior she either gets bored, yells at me to stop talking because she doesn’t like the topic, or just ignore me. If you have any advice please tell me, I’m tired of walking on eggshells around her and getting hit, I just want to be a good big sister and make her feel safe with me and give her a space my older sister didn’t.