I deposited a check and it bounced (the funds were withdrawn from my account). How do I categorized the cash outflow withdrawl?

You should categorize the outflow to the same account that the original inflow (deposit) was categorized to. The result is that the original inflow and the subsequent bounced entry will balance each other out, in the same account. 

For example if you deposited a check and it was categorized to Sales of Product Income - Invoices and Cash, and then a few days later the check bounced and it the funds were withdrawn from your bank account, you can categorize the withdrawal also to the Sales of Product Income - Invoices and Cash account.