Take a look at the Alarm section in the hand book. You need to set the Alarm to "Reduced Guard" in the Alarm part of the S-Max�s in dash menu system. This will disable the interior sensors. (But only until the next time you start the car - at which point it reverts to "Full Guard")
There is also an "Ask on Exit" option that will ask which Alarm mode to use each time you turn off the ignition.
A single press on the remote button means that the locks are not double locked i.e. the interior handles still open the doors. This makes no difference to the Alarm mode. (Single locking is also recommended if you are leaving kids or pets in the car as it makes it easier to gain access in an emergency)