At random times my screen will be frozen. When I hit the back button a horizontal line comes from the top of the screen and travels to the bottom of the screen and then the screen is back to responding. Happens just occasionally. I had a Motorola phone prior to my Note 9 and this would also happen on that phone. I got my Note 9 and transferred my contacts / Apps ect... Which makes me think it's a app I have downloaded...? Help please.
The only real way to find out which application it is would be to disable or uninstall them one at a time.