Below the list of shares on the first page is a button which will make the current configuration active. This is done by stopping and starting the running NFS server processes.
Solaris does not allow you to re-export a directory NFS mounted from another server - only directories on local filesystems can be exported. If a shared directory contains the mount point of another local filesystem, NFS clients of that share will not see files below that mount point. The server must re-export each local filesystem separately, to be mounted by clients at the correct point in the directory hierarchy.