Noises During Shifting problems of the 2018 GMC Acadia

1* purchased March 2018 (acadia denali) since August 2018 in motion when I accelerate it sounds like a loud lawnmower & crackling sound in rear muffler area. Took it chevy place in glenpool, ok. They couldn't find anything. 2* on 2 occassions, in motion, the car accelerated with a loud noise & as if it were getting power & not moving then jerks & speeds up about 15mph faster & I couldn't stop it. I kept slamming on my breaks, but the break would only go in so far. I was frightened with my 2 young boys in car screaming. It's like riding a horse & it takes off & you can't control it. 3* on about 8 or 9 occassions stationary I get out of my car & it makes a really loud annoying sound like a machine/robot powering down. My kids always say, it's going to blow up 4* the most annoying, for past month. . . Stationary, every single day & time I turn my ignition off. It has loud beeping sound & check rear seat flashing on screen then shift into park flashes. This occurs every single time I turn my car off. Sometimes I have to just let it go on all day because I can't get it stop. I turn car on & off shift back & forth & it still will not go off. Sometimes it does after long periods of time. I don't have time to struggle with getting a car into park every single time I turn my ignition off. I have to beat it forward hard with my hand to the point my wrist is bruised. Now I have to use my foot to kick gear shifter into park. I'm afraid t's going to roll out & or down and hit something, someone or even one of my children. Which would not be good. I've seen several of same complaints. This really needs to be investigated & recalled ASAP. My elderly mother had to call my brother to another part of town to beat the gear shift into park. This car was brand new & I shouldn't have any of the above mentioned issues. It's frustrating thinking GMC was top of the line & it's not.