How do I make the hitbox change to current animation

So, I have a game with "spiderman" video game character, I have it set up as "player 1" which is a transparent square and a "spiderman_pin" which is the sprite which pins on to the player_1. Now, I wanna add bullets, but I just dont want them to register the bullets being hit in the most random spot. so, how do I change the hitbox to the current animation?

In the 'edit animation' screen on the left you see a couple buttons. The bottom one is 'Set collision polygon. That is where you adjust the hitbox pretty much. Right click on a sprite and select 'Edit animations' to get there.