IPS engine updates

It seems my ips engine never udpdates. I have Fortigate 5.6.6 with IPS engine Version 3.00538

Fortigate announces updates, are they automatic? what do I have to do? what is the normal procedure to update IPS?

I don't have any problem with the IPs but I would like to know if it is something wrong:

"A new IPS engine version 3.532 will be released from the FortiGuard Distribution Network in a phased approach starting on July 31^st.  It will be released to FortiGate devices with a valid IPS subscription running FortiOS version 5.6.  "

Thanks