If you turn auto-loading off you can switch around the eels any way you like, as long as you have at least one empty slot in your reserves
your torpedo crew will mutiny after a while though...
"Nein, Nein, Nein, Jungs, der Zaunkonig soll doch im rohr 1 gesteckt werden, der Lut I in 2 und die andere mit dem TIIIs ja, hol die den wieder raus und versuchen sie es noch 'nen' mal!"
after doing that three times they'll be dead tired, but still awake enough to plot revenge
what bugs me most is not being able to get the aft externals forward on a type IX
Oh well, if I want all those little quirks and peculiarities of the basic boats to go away I'll take a XXI for a spin