Product Variations

Hi, I am trying to add an additional product variation to one of my products but it is only allowing 2 options, I need a 3rd colour option – this is the link http://www.popitopeners.co.nz/product/3-pack-pop-it-plastic/
Does anyone know how to add an additional option? Im still learning WordPress.
Could it be because I need to update my theme version?

https://wordpress.org/plugins/woocommerce/