Here you have good tutorials about submarines.
"Show truth
on" is not good option for learning. You should switch this mode only for corrections (only for few secounds). You can turn on "Child settings" via AutoCrew on some stations.
Most players in MP session have AutoCrew On for:
SUBMARINES
- TMA
- Active intercept
SURFACE
- TMA
- ESM
- Active intercept
- Countermeasures
HELO/AIR
- ESM
- RADAR