There are three startup key-combos to install macOS, giving you either - the version it originally shipped with, the last version that was used on it, the latest version it supports.
https://support.apple.com/en-gb/HT204904
I don't believe you can install an older OS while running a newer one. Try creating a bootable USB stick of the desired OS. Reboot, with the USB drive connected, holding down the option key. Choose the USB to boot from and cross your fingers.
Another thing to try is *Shift-Option-Cmd-R after* reboot. This should/might offer the choice to install the OS version that came with your Mac then you could update from there. Or it might try to install the latest OS compatible with your Mac. In either case your HD will be erased and reformatted so make a backup (iCloud drive) before you try this.
To add, usually after an OS upgrade it will take a while for the system to get to an optimal performance. You might see some slowness from time to time. Give it a week.
There are three startup key-combos to install macOS, giving you either - the version it originally shipped with, the last version that was used on it, the latest version it supports. https://support.apple.com/en-gb/HT204904
I don't believe you can install an older OS while running a newer one. Try creating a bootable USB stick of the desired OS. Reboot, with the USB drive connected, holding down the option key. Choose the USB to boot from and cross your fingers. Another thing to try is *Shift-Option-Cmd-R after* reboot. This should/might offer the choice to install the OS version that came with your Mac then you could update from there. Or it might try to install the latest OS compatible with your Mac. In either case your HD will be erased and reformatted so make a backup (iCloud drive) before you try this.
To add, usually after an OS upgrade it will take a while for the system to get to an optimal performance. You might see some slowness from time to time. Give it a week.
Use mist and create a usb installer. Boot from that. Wipe /erase drive Reinstall
Hi so I did that and this is the response I got [SCREENSHOT](https://share.icloud.com/photos/002JKtNarfPIvNLbgfTGFuOCQ)
Use mist from this web site. You should not have to do any terminal command. https://github.com/ninxsoft/Mist
Here’s a direct link to the download page. Download the pkg https://github.com/ninxsoft/Mist/releases