With the headslot, you can change the slot where the head will appear when the player enters. If you are updating from older versions, you can delete the config.yml file or add headslot: at the very bottom (do not use tabs, use 4 spaces). Keep in mind that counting starts from 0, meaning that if you want to place the head in slot 3, you will need to put 2.

Added comments in config.yml file