The latest SS software remembers the last switch setting so if you turned it off before you switched the ignition off it will still be off when you restart, I think this version was standard from 2013 on so most likely not on your car unless it was upgraded
Is it possible to get the software in my care updated to include this feature?
(Not that I am necessarily intending to get the SS disabled on my 2010 500c dualogic, I have only had the car for a couple of days...and I find SS disconcerting, especially when parking... but obviously I need to get used to it first...)