• Startup page: server name, game mode (survival / creative / adventure), difficulty and cheats. Restart to apply.
• Other settings are in server.properties in the file manager (for example level-name, view-distance, allow-list). Fields managed by the panel (port, name, game mode, difficulty, max players) are overwritten from the Startup page.
• Make someone operator: in the Console, run op GamerTag. Use deop to remove.
• Allowlist: set allow-list=true in server.properties, then run allowlist add GamerTag in the Console.
• Upload a world: stop the server, upload the world folder to worlds/, and set level-name in server.properties to that folder's name.