Well training is quite a long process, it takes 3-4 seasons until a trainee is really good.
You have 2 good ones in Edu Bueno and Allan Neil.
You should do one-position training and make sure they both avec 48+ minutes a that position. It doesn't really matter if their prefered position is not the one you're training at. For example if you train passing, you have to make them play at the PG position, if you train rebounding, you have to make them play at C.
1 position training is always more effective than 2 position training, and so on, so keep that in mind. It's better to concentrate on a few trainees rather than trying to train all your team
Read the user manual, there's a lot of good information in it!