I remember this movie that I have watched two or three times. Here is what I remember:
It starts with a girl flying a remote control UFO, she wants to perfect one of her tricks.
She goes to this research lab where I think an elderly friend of hers works.
Later, she believes that she is a martian/alien.
She shaves her hair, saying that hair gives martians rashes or something.
She runs away, and she has a power called the silent scream where she looks as if she is screaming. She shatters windows like this.
In the end she steals/borrows a weather balloon(?) and flies away.
That is all that I remember. Thanks in advance!