First thing to check is your Options / Gameplay settings on the menus. For the Main Menu, in which your Single Missions, War Patrols, Sub School, and MultiPlayer are configured, you use the Options and then Gameplay Settings
Stock Main Menu
However, if you are doing a career, you have to use the menu you get to by clicking on the wooden radio console to the left side of the Captain's Office prior to going on patrol. Choose Gameplay Settings there also. Each career can have its own set of options set:
FotRSU's Captain's Office:
Note that the box for Dud Torpedoes in the Capatain's Office is empty, so there will not be dud torpedoes. So make certain you have Dud Torpedoes turned-off in both of those menus. Then, if you still have issues, you would use
Silent3Ditor to open the Data /Library / Torpedoes_US.dat file, highlight the desired torpedo you want to edit, select its ID in the upper middle, Ctrl-C to copy the number (such as 0x8f346dcc43bfbcb2), then click on the "sim" file link in the upper right of the window, and once in that file, use the "Edit - Find" menu (Ctrl-F) and use Ctrl-V to paste that ID number into the Find dialog. 'Search', and it should highlight the appropriate "amun_torpedo" for the desired torpedo. Select the settings below the found item, and edit the desired settings in there, whether it'd be guidance or pistol. Note that there are several of those settings that deal with dates and angles of impact...