Help, Trouble hitting targets

[2pfspiff]

Good day My name is Brian and I am new to Uboat and Sub games in general. I am having issues with targeting solutions. I have watched several videos and even made a note book for quick reference, but in the training mission for torpedo targeting I keep missing the target by a lot.
Some things that I am doing are taking over in manual. I am not perfectly horizontal with the target and the Uboat is moving. Should I make myself perfectly Horizontal and stop moving when I fire? Also what is the best distance to be when firing? Last when using the tool to measure distance with the ghost image in the periscope does it mater if it is magnified or does it need to be a standard Zoom?
These are some of the issues that I feel may be the issue. Your help is greatly appreciated. Thank you