10.11.4 still not working right

1. It only needs "fixed" for those users it matters to.

2. Install Mountain Lion.

Can you be a bit more specific? What Finder windows? And why should they open at startup?

Tyler the Wolf wrote:

All Finder windows that were open before I turned off the computer. They have been opening at startup since 1984 and should continue to do that. For those who don't like them to open an option to turn that off can be coded in.

1. If you want your open Finder windows to return when you restart your computer, go to System Preferences --> General and make sure "Close windows when quitting an app" is not checked.
2. You can't install an OS on a computer older than the OS that came with it. So, if your computer came with Yosemite, you can't install an operating system older than that. Therefore, you cannot go back to Mountain Lion.

Tyler the Wolf wrote:

Believe me, I tried many times. This machine came as a refurbished with Yosemite installed and just won't let me go back to Mountain Lion.

Your model of iMac came pre-installed with Mountain Lion. Therefor, despite buying it with Yosemite installed. If you do an internet recovery it should install Mountain Lion.

Tyler the Wolf wrote:

The hard drive has been reformatted since (I bought it about a year ago).

and?

Tyler the Wolf wrote:

The hard drive has been reformatted since (I bought it about a year ago).

Have you tried Internet Recovery to restore the computer to what came on it when it was originally made?

Which version of OS X is installed by OS X Recovery?

• If you use the Recovery System stored on your startup drive to reinstall OS X, it installs the most recent version of OS X previously installed on this computer.
• If you use Internet Recovery to reinstall OS X, it installs the version of OS X that originally came with your computer. After installation is finished, use the Mac App Store to install related updates or later versions of OS X that you have previously purchased.

OS X: About OS X Recovery - Apple Support

Tyler the Wolf wrote:

1) It is not checked; the Finder windows won't open anyway.

pinkstones is correct. Of course when you restart "Reopen windows when logging back in" has to be checked.

Tyler the Wolf wrote:

How does it know what it originally came with when the drive has been reformatted?

When you say you reformatted the hard drive, what precisely did you do? Wipe the disk clean? Reinstall the operating system?

Tyler the Wolf wrote:

How does it know what it originally came with when the drive has been reformatted?

The same way it knows if you buy a new Mac with OSX 10.11 pre-installed you can't run any earlier version no matter how many times you reformat the drive.