Hey, I'm a girl 11 years old, and I have a trouble and it's really annoying me,
Im arabian and I'm speak english us&uk&spanish&french&korean&japanese,and when I talk to anybody I say some words in arabic and some words in the other languages, even I starting forgoting the arabian words,one of the time I was talking to Daughter of my Aunt, she was 4 years old she show me a hippo pic and she asked me what is it I told her it's a hippopotomus|in english| and I told her I forgot what does it mean in arabic,what shouhld I do?

What to do? Be happy you are so multilingual!! I totally envy you.

But my friends at school doesn't understand me when I talk to them

Teach them new words.

They forgot

Remind them.

Make sure that you are learning one language at a time, and start making a difference between them. I speak English, Spanish, French, Portuguese, and a little Italian (not fluent YET)... takes a while, but you will master them slowly.