You should most likely generate a unique one for each website, but I doubt any attacker is going to go to the trouble of capturing that once and trying it again as a security answer elsewhere.
Bones. I'm sorry but you weren't my first dog. My first dog will forever be the answer when it comes to security questions. It's convenient. But you're really my favorite. I love you bones.
Don't use real answers. "Security" questions have the same 'authority' as passwords (they can be used to change your password), but are often not treated with the same level of care as actual passwords.
Meaning, SQ are often easier for a hacker to figure out and exploit. In that event, SQs are actually worse than passwords, because they're "unchangeable" (well, the real answer is). So if an SQ answer gets compromised, you're SOL
The best option is to use a password manager, and randomly generate passwords and SQ answers (i use 1Password, but there are other good options)
Edit: oh and, if you use real answers, then those are more likely to be publicly searchable on Facebook or socially engineered (like a "which dog are you" quiz)
How is even having these security questions even considered safe? What is more likely, person to know your password or a name of your favorite dog that you might get from that person's Facebook account?
Even to the point of being nonsensical. I've had tech support chuckle at me but the intent was clear as day. Anyone can find my mother's maiden name. Good luck figuring out the answer I gave the bank.