Hi Looney,
what i do is go to torpedo settings, push the button, set the speed to e.g. 8 knots, and then again push the button. It can now not be changed with the mouse. Then i set all tubes to 1 meter, impact etc,, open the tubes, and finally make the check through UZO/periscope, adjusting range and AOB.
I take it that now those speed settings should remain as i set it (=8 knots), as long as i do not request anyt automatic speed guess at the notepad again - what i did not do.
Well, i will continue to try, maybe i'll find out ... or not
Thanks, and a happy weekend
Catfish