Account is you. Settings is the community. Mixing them up is the most common question.
Profile
Under Account → Profile: photo, name, bio, city. It's what other members see next to your posts.
Password
Under Account → Security. If you forgot it, use "recover" on the sign-in screen — the link arrives by email and expires.
Language and theme
The language selector and the light/dark switch sit at the top of the site. The choice is yours and applies across all your communities — it doesn't change the community's language for anyone else.
Your plan's billing
Under Account → Billing you see the Cool plan you're on, the invoice history and the cancel button. Cancelling doesn't delete the community: it drops back to the Começo plan.