We are working hard to make Tutanota more secure every day: We will soon enable hardware key support for the Tutanota desktop clients! 🥳🥳 Check here how you can best protect your login credentials: https://tutanota.com/blog/posts/login-security-best-practice/
The best way to keep your login credentials safe is to literally write them down in a notebook and keep that notebook somewhere safe.
@inachara It does depend on your threat model but paper isn't that safe either, unless you are using some kind of cipher. However, that would get really tedious. For most people, I would recommend keeping sensitive data in an external encrypted hard drive. You can use something like @cryptomator or #KeePassXC.