How do I start multiple bounties? I just started one and there's no obvious way to start another one.
You can't assign more than one bounty to a question at a time. From the Bounty Help:
Questions may only have one active question bounty at any given time.
Note that you can have more than one active bounty, but these have to be assigned to different questions:
Users may only have three active bounties at any given time.