I can move my testicles from their vertical position to horizontal and then back to vertical , does that mean that i have bell clapper deformity and will surely have torsion?or i can wear a good underwear and prevent torsion for life?

Your obsession with your testicles is concerning. If you get severe pain, see a doctor, otherwise leave your balls alone.

Testicles are mobile structures so the ability to move them from one to another position does not mean you have Bell-clapper deformity. Keep wear ing a support underwear. Nothing in this world is guaranteed. I think you will be fine