Problem with second monitor operation
I purchased a new 2020 iMac. I connected my old iMac (2011) as a second monitor via usb cable (adapter). I started my new Mac, I then pressed "command" + F2 and the second monitor worked perfectly. When I put the new Mac to sleep or turn it off both monitors go black (asleep). But when I restart the new Mac I have to (again) press the command F2 key to command the second monitor to perform as a second monitor. Is there a way to command the second monitor to always perform as a second monitor? I have called A[ple 2 times and they can't figure it out.