I want to set my project root key so that all the cubase samples from media will be in the same key (in this case C major). I only just found out this was possible and all the help I can find about it online doesnt seem to apply to cubase 11. There is no popup in the project menu option and there is no dropdown onscreen anywhere I can see. How on earth do you do this ?
The Project Root Key is found in the toolbar at top of the project window. If you can’t see it there, you may need to make it visisble by the “Set up Toolbar” button. It’s the cogwheel button at the very top right of the project window.
In addition to what Steve has posted above, You may need to right click at the top bar and enable the ‘Project Root Key’ control to be on-screen too:-
To get the visibility menu up to define what appears on your top toolbar, simply right click where i’ve circled red. Or hit the cog button (Circled blue).
Edit: Sorry, i see @Starsprinkler has posted in the meantime, I’ll keep the screenshot here as it may help. 
yes, there is no such item on the menu
Then you must be using a cut-down version of the software.
cubase 11 pro version
I’m actually not sure of what you mean. But the opther posts from @skijumptoes and @Starsprinkler are correct, so maybe re-read?
I managed to find it eventually, I had to set the property from the menu when I activated the cog menu, thanks for your help guys