Changing seating config

I thought this had already been answered, but I can’t seem to find it, so please excuse me if this a repeat Q.

I have a an aircraft that is operating in an experimental seating configuration. It is currently flying a full schedule and is booked days out. I want to change the seating configuration to make it the same as my other aircraft (less total seats). How do I do this? If I change it now what will happen to the current booking?

It will take at least 72 hours until the first flight with the new configuration takes off. Already booked flights will still use your old configuration.