If you have access to your current MetaTrader password and wish to change the password from your iOS device, you have to go through some simple steps first. 

  1. From your MetaTrader, tap the Setting button. 
  2. Tap the Account you wish to change the password to. 
  3. Tap the 3 horizontal dots

  4. Tap Change Password.
  5. Tap Change Master Password.

  6. Insert your Current Password, type in your New Password and Confirm the New Password in the given blank space.
  7. When done, tap Change. 
  8. Your password is now changed.