How to change OSX System (Default) Shortcuts?

This is pretty easy. I already answered a similar question for someone who wanted to redefine Command-V here.

Basically you need to go into System Preferences > Keyboard > Shortcuts and define a new shortcut under "All Apps". If you don't want to change it to something useful you will have to define a shortcut you will never use such as Shift-Command-Option-1.

If you want to get rid of all the shortcuts then I suggest 'Karabiner-Elements' and spend some time understanding how to write a private.xml config file for it. You might also want to grab a copy of 'Key Codes' so you can figure out which keys push out which keycodes and modifiers.

It's certainly possible to map the "Log Out …" as Shift-Command-Q out of the way. You just enter it into Shortcuts with the name and the ellipsis and the shortcut no longer works. Command-Q is impossible with the shortcut method but it was the only one I could find.

(I also wouldn't be rude and peremptory to people who were trying to help me but that could just be me.)

Go into System Preferences > Keyboard > Shortcuts, select Accessibility on left Pane and check "Invert colors" shortcut. Initially it's disabled.

Modify it to command+Q so from now this shortcut will not close anymore apps, it will just invert colors. It's an easy way to get rid of the habit to hit command+Q.