If the syslog configuration is not in the startup-configuration file, it will not be preserved after a reboot. Once you have the switch configured and everything including syslog is working, you can run the CLI command "wr" for write, or the command " copy run start ".
Buffer of the switch log is not configurable and is short for switch memory reason. This is why a syslog is used, when needed.
This is a NV1550 , so it should be running the EMR firmware release. If it has not been upgraded since it was taken out of the box, you will experience many bad issues. Shipping firmware is only to allow upgrading to the Supported EMR release.