Did you use sudo when creating the certificate, or allow a script to do so? If so, it is owned by root and you may need to use a root shell or sudo in order to view or change it.
(The operating system will distinguish between things that can be done by an ordinary user and system administration things that require administrative access.)
You should use sudo to view the certificates. (Note that you can’t sudo cd because cd is a shell built-in command. If you need a shell where you can cd into directories that you don’t have permissions for, you can use sudo -s to get a root shell.)