Does this mean you have to shoot to use it? Or can you just break a target lock on someone.

I'm talking about Hobbie's ability

you have to use the target lock, you cant just drop it. although... changing it to someone else through some means (dutch) counts as acquiring the lock for his ability.

You can use it on 0 dice though. So when you attack even if you don't want to change your dice results you can 'use' the target lock.

But only during an attack.

Cool

There are a couple other ways to spend a TL other than modifying attack dice, notably:

• R7 Astromech : Once per round when defending, if you have a target lock on the attacker, you may spend the target lock to choose any or all attack dice. The attacker must reroll the chosen dice.
• Firing any missile or torpedo that tells you to "Spend your target lock"