How to make the motor turn the other way
Reverse the current
If you reverse the battery, you also reverse the current supply. Using Flemings left hand rule (i.e. electricity passing through the wire (Left = Electricity in wire)) you can see below that the forces on the wire reverse and therefore the motor spins in the other direction.
Reverse the magnetic field
Again using Flemings left hand rule you can see that the forces on the wire have reversed. The spinning shaft of the motor will spin in the other direction.
Reverse the current and the magnetic field
If you reverse the current and the magnetic field as far as the direction of the spinning shaft goes there is NO CHANGE.
This can again be verified using Flemings left hand rule.