<human>: Can you give me a shortened version of the text?

First of all, I don't know if this is the right sub for this and if this post is wrongly put here I'll delete it. 

Anyways as the title says I have no idea on how to deal with my ignorant sister (I'm 18 and she's 14). Normally I would let the person in question just go on with his or her life without me really beeing around him but in this case it's my sister and I don't really have a way to get away from her until I move. And as if the ignorant thing wasn't enough she's one of the most stubborn human beings I've ever met and if she thinks she's right on a subject no arguments or any logic will seem to change her opinion. She's pretty well informed and studies a lot witch makes most her points valid but how quick she's to judge people and how little she seems to care about "stupid people"  (usually referencing to smokers, people who fight and/or actual stupid people) makes some of her comments true cringe material. 

I feel like the usual comment on how it would be more efficient to bang my face in a rock for an hour would be a better use of energy than arguing with her but since she's my sister and both me, my parents and my oldest little sister (except for her) are getting real tired of her arguing, complaining and generall bitching, I feel like it's worth the work. The biggest problem for me since I kind of know what I want her to realize is how to make her realize this and how to not make it seem like I'm sort of attacking her. 

Do you have any idea on how to go about this or should I just try to stay away from it until I move (I'll probably move for collage in the autumn)? 

Sorry for spelling and/or grammar mistakes but English isn't my first  language.
<bot>: My sister is having huge problems accepting that different people think different and have other opinions than her "correct"  ones.