How to give a cavalier a Heavy Warhorse

[Viperian]

When creating a cavalier and you add its mount (Cavalier tab > Animal Companion link), you can select a Horse, but there's no option to select a heavy horse.

Once you select "Horse" as the cavalier's companion, you can then edit the animal companion, but I can't find where to make it a heavy horse.

In the Pathfinder Bestiary, there's only one entry for Horse, and under that it specifies that heavy horses gain the "advanced simple template." I've looked in HeroLab under my cavalier's horse animal companion but can't find where to give it the advanced simple template.

There's a significant difference between a regular horse and a war-trained, heavy warhorse, and when I output the character to text or the character sheet PDF, I'd like to see the statistics for the companion as a heavy horse, with proper attack bonuses, number and type of attacks, etc.

Any tips or advice would be greatly appreciated!