Driver door locking control button

[Mikomotor]

Hi,

I've just purchased a 2006 Murano here in London. As the Handbook is less than helpful re. the above, can anyone please direct me to a simple explanation of how the driver's door locking button works?

I'm guessing that there must be some form of sequence as we have all doors unlocked (green key shown on instrument panel) but then other presses seem to give us both back doors locked (from inside) with front passenger unlocked, and then vice versa! Help!

Many thanks and Happy New Year to all!

Mike.