Point taken about the domelights.
Following your comments,in my installation of FSX,pressing Shift+L does indeed switch on the passengers lights,however,
switching the "Light Override" switch to "Override" appears to do the same.
This may be the answer to the original question
I am new to the 707 and indeed to the forum,so I have no idea if this is a coincidence or what happens in real life.
I imagine that in the real thing,each passenger would have their own switches,but the crew have the override switch to maintain overall control?

Regards,
Nick.