Log out options

[JonE]

How can I change (lengthen) the amount of wait time before the forum logs me out? It takes me several minutes to compose my thoughtful, detailed, insightful (i.e. long) posts, and I often get booted out. There's no obvious place for it under the user control panel.

I suppose I could stop being thoughtful, detailed, and insightful, but that wouldn't be very HQ, would it?

Thanks in advance.