When changing the running number, You put a train WITH a running number and click on the question mark button below the slot where you see all your locomotives and rollingstock appear. Then click on the currnent engine after you have clicked the button. There will be a slot that has a number or no number. Click on that and then give it a new number.
Did what Enzo1 said thanks but no joy can change number in pop up
but no show on cab
I have modified in C C P to build 2.9 & changed interior to 9f cab shell
also now shows obsolete