2009 Kia Amanti- starter stays engaged when i start car

2009 Kia Amanti 122k Miles daily driver (for work, a lot of turning on and off). when i start the car the starter stays engaged and it makes the screeching sound and sometimes if i wiggle the key it stops other wise itll just keep making the screeching sound until i turn the car off or put it in drive or reverse.
there are also times when i start the car and itll be fine (in park) and out of nowhere the starter will engage and start making noise. there has been a few times also when i dont even turn the car on, i just get in the car turn the key in the AUX position and all my dash lights are on and out of nowhere the car will try to start itself and the screeching grinding noise will start all over again. i just replaced the starter due to all this happening my last(factory)starter had to be replaced and i replaced the ignition(the key tumbler) because someone told me thats what is was, but it was not it. so after replacing the 2 parts the starter is still engaging when the car starts. HELP ME! this is an odd problem