"Self-Sign" Cert Questions

version 5.6.7

In System -> Settings, the HTTPS cert is set to "self-sign"

but in System -> Certificates, there is no cert with that name.

If I change this to the only other option "Fortinet_Factory", I notice two things.

This is definitely a different cert.

I do not get the option to change it back to "self-sign", it's gone from the list.

On most of my units, "self-sign" is signed with SHA-256 and "Fortinet_Factory" is SHA-1, but I have one Fortimanager ADOM where "self-sign" is still SHA-1 and it's failing PCI audit.  I would like to avoid manually generating my own self-signed certs if possible to correct this, it seems like it should be doable.

Any insight appreciated.