In your Account Settings, there is an option called Safe Session Duration. By default, this is on, and protects your account by limiting the length of your sessions and by only extending them when you are active.
This practice helps secure your account, but it can be annoying. A few users have expressed the desire for a longer timeout.
Starting today, if the Safe Session Duration setting is unchecked, your maximum session length will be increased from 1 day to 30 days. You will be logged out in order for the setting to take effect.