At 3rd level, you commit to an order of blood hunter martial focus. Choose Order of the Ghostslayer, Order of the Profane Soul, Order of the Mutant, or Order of the Lycan, all detailed at the end of the class description. The order you choose grants you features at 3rd level, and again at 7th, 11th, 15th, and 18th level. even though it says this no options appear between any of those levels to change your order.

You don't change your other at those levels, you pick an order at third level, which then determines which features you get at those levels