It is ALWAYS ON. You can double-check by going to dashboard and from the first dashboard page click the small arrow next to the CPU and RAM guage and in the popup screen click Process. You should be able to scroll through the list of running processes and see the name smbd - that the SAMBA daemon running on the server.
By default SAMBA is set to run at version 2.0 but if you have Windows 8 or later, you can change the SAMBA version to 3.0 (since Win8 supports 3.0, which offers improved performance). To change it, go to dashboard → Settings → Network → Windows Services → (choose from dropdown list) Max SMB Protocol → SMB 3
If this helps you, please click the star under my username to the left of this post to give me a kudo.
