What is happening when you say "layers are not working" on your second monitor? Do they work on your primary? What is your setup?
Can you share a screenshot - your problem makes no sense.
Are you talking about the layers inside of Photoshop?
You said you replaced the computer and downloaded the latest version of Photoshop and the same problem is still there.
I wonder if the problem may be your secondary monitor.
If this isn't the issue, then I agree, you will need to provide more information so that we can help you troubleshoot this issue.