What do I set in settings?

Einstellungen is the place for behaviour, not for your actual work: language, design, optional authenticator, notifications, privacy, access keys and dangerous account actions.

Steps

Open Einstellungen.
Choose language and theme. Automatic follows the device language. If that is missing, German applies.
Turn Morgenappell per E-Mail and Einladungen per E-Mail on or off.
Decide whether automatic tasks should run.
Under Sicherheit you can optionally set up an authenticator app. The next sign-in then asks for a code.
Use Daten zurücksetzen or Konto löschen only after you have read the consequences.

What you should know

The automation switch controls night work and the Morgenappell. Less automation means less background work and fewer prepared suggestions. Open invoices and unbilled jobs stay visible in the app.

Some account emails stay on: a failed subscription payment, a payment request, a dispute (opened or lost), a failed payout, a failed letter send. That cannot be switched off.

The authenticator is optional. Without a set-up app, sign-in stays as it is.

If something goes wrong

If you started a hard account action, read the confirmation carefully. Daten zurücksetzen and Konto löschen are not the same.

If the authenticator code is rejected, check the time on the phone and try the current code.

Questions

Where do I change billing?

Via Abrechnung. Settings links there, but is not the payment overview.

Where do I decide about product analytics?

In the privacy area, choose Give consent or Decline. Product analytics and session replay run only after you consent. The choice is stored only in this browser and can be changed there at any time.

Do I have to set up an authenticator app?

No. If you set one up, Uely-3000 asks for a code from the app after sign-in.