Sonarr - folder not writeable by user 'root'


I am new to the Snap store. I have just installed Sonarr, and I’m seeing the following notification in the Status section:-

Cannot install update because startup folder ‘/snap/sonarr/301/Sonarr’ is not writable by the user ‘root’.

The permissions on that folder are already set to 755, and the owner is root.

I tried to manually change the permissions to 777, but I get the message:-

chmod: changing permissions of ‘Sonarr’: Read-only file system

Is this because the application and dependencies are self-contained? If so, how do I modify the folder permissions so that Sonarr can auto-update?

Thank you.