Why did the hijackers decide to crash the plane?

I certainly don't want to start anything here......but that plane did not crash...it was blown out of the sky. Don't rely on a fake movie...do your research and you will find the answers. Don't believe me?
For starters...when a plane crashes, most of the parts of the plane and contents are found fairly close...right? One of the engines from flight 93 was found EIGHT MILES away from the site. Why no plane parts at all(at the site)?
Second, for that flight only...the flight number was changed to 93.
Third, there is a video of a white plane with no numbers or marking filmed right before Flight 93 was shot down. I've even heard who owned that white plane...but I'm certainly not going to say it on an open board. But the info is out there.
I have studied all of 9-11 since the day it happened. I have devoted MANY HOURS, DAYS, MONTHS AND YEARS studying 9-11. And I did it with an open mind. Not believing one way or the other....till I connected all the dots that Bush said to.
I'm sorry if I upset anyone.....and will not come back to argue....that's not why I wrote this. Just stating my opinion and research results.

Why did they all of the sudden decide to crash the plane into Pennsylvania instead of head for their target? Did I miss something?