I remember when the M7 first came out with LIRR and the marker lights were switched off by default at the other end of the train so I would do a marathon 10 cars down to the other end of the train to turn them back on, it was annoying and I'm glad you shortly updated it so these were on by default and all i had to do is turn the front ones off without leaving the seat. Now the M3 is the same as when the M7 was released, you gotta do a long run to the back of the train at the start of the service to turn them on, i know i don't have to but it just adds to the immersion playing with them on and I'm slight ocd about these sort of things. So could you maybe consider updating it so the M3 marker lights are like the M7 to eliminate that need to run a total of 20 car lengths at the start of the service?
If you can use a keyboard - you can use the button to the left of Backspace (+Ctrl) to switch between the driver's cab views.