How do I change options on the chatbox?

Freenode's new chatbox allows you to adjust certain options. Once logged in (note that if you're not logged in, the options will still work, but will not save for the next time you log in), click the small IRC logo in the top left corner, then click "Options."

Here you can change several things about the box. When you have the options you want, hit "Save." These preferences will be saved for the next time you log in on the same account. Note that these options will only be saved if you use the on-site page, chat clients have their own options selection.

See also:
What to do if you have a problem with our chatbox
Chat Clients to Bypass Site Chatbox