changing permissions sudo

I am using a Xubuntu guest(VM) on OpenSUSE Leap host.
I change permissions in "/mnt/shared" and it shows "Operation not permitted" despite that I'm doing it as sudo. What is going wrong?

Are you trying to mnt a shared folder?

https://forums.virtualbox.org/viewtopic.php?f=7&t=47815

Changing ownership might be another way to get around it.
http://www.linuxnix.com/chown-comman...ined-examples/

Is this more of what you have going on?
http://unix.stackexchange.com/questi...ntu-guest-wind

Check out this link also for file and folder permissions:
https://www.linux.com/learn/how-mana...missions-linux