Keyboard Shortcut Not Working

I have several accounts on the iMac "shift cmd c" works as it should on every account bar one.

In order to get the same outcome as "shift cmd c" on my main account I have to utilise the fn key:

fn shift cmd c

Why?

In fact the "why" is not important; I would just like the shortcut "shift cmd c" to do what it does on every other account, without my holding down the fn key.

I have attempted the following System Preferences/ Keyboard/ Shortcuts/ App Shortcuts + (either) All Applications (or) Finder "shift cmd c" and nothing happens.

I have looked though as many apps as I can to see if there is a conflict but none appears apparent.

Any ideas?