Like gravitation forces, magnetic forces have an inverse square
relationship. The other planets are so far away from the earth, they just
don't make a bit of difference, even when lined up perfectly. Read that
NASA article, and understand that the ideas are applicable to magnetic
forces as well as gravitational forces.
>Normally the magnetic field does some major things, like cause our planet
>to spin and align in a certain way
You have this backwards. The magnetic field is caused by the spin of the
earth, which causes circulation of liquid metalic matter in the core.