Your follows, read chapters, reading status and lists, the same in Usherr and on MangaDex. Optional, and each person connects their own.
In Broadcast: You, Your settings, MangaDex account.
In Classic or Neu: Settings, Library, MangaDex account.
Under You, Your settings (in Classic or Neu: Settings, Library), or the MangaDex account button on the Manga page). Manga has to be switched on.
Sign in on mangadex.org, open Settings, API Clients, and make a new personal client (any name will do). Wait until MangaDex approves it, then copy its client id and its secret.
Fill in the Client id, Client secret, your MangaDex username and password, and press Connect. Usherr saves them encrypted, sends them only to MangaDex, and never shows them again.
Chapters you read are marked on MangaDex within minutes; follows, history, reading status and lists every half hour; and everything each night between 2 and 9. Sync now does it straight away. Series you follow there come into Manga, and the Manga page shows new chapters of what you follow, what you read lately on MangaDex, and your lists.
Follow, your reading status (Reading, On hold, Plan to read…) and your MangaDex lists, kept the same on both.
18+ series stay out unless the NSFW section is on for you. Disconnect deletes the saved sign-in and everything Usherr kept from MangaDex; nothing changes on MangaDex.