Sorry for not being specific in my post, but I wasn't sure how to word it. Basically I was shooting some scorpions, and it was letting me choose where I wanted to shoot, like in the head, tail, eyes, etc. but now all of a sudden it's not letting me choose?

Did you pick any perks/traits involving Fast Shot??

No, I didn't pick any of the optional traits. It does say my eyes are damaged. Does that have something to do with it? And if so, how do I fix it?

You have to do the aimed shot rather than the normal shot to target sections, are you sure you haven't accidently changed back to normal shot?

Not sure. How do I change it?

in the middle icon of your interface at the bottom of your screen you should see your current chosen weapon and the AP amount it takes to shoot it. If you RIGHT click on it, it will change modes from normal shot, targeted shot (shown by a crosshairs), or reload. Once you change it, then left click, it will perform whatever action you have chosen.
To get the option of picking a body part it has to be showing the little crosshairs icon.
But having your eyes damaged will hurt your accuracy, so try to find a doctor somewhere who can fix that up for ya, or have someone in your party use a doctors bag (assuming they have some ability)

Keep in mind that this uses up one more action point than a regular, unaimed shot.