Is there a way to configure password auto-generation in Safari?
I'm not aware of any way to do this in Safari, but you can always generate new passwords in System Preferences instead:


Open Users and Groups preferences.
Go as if to change your password.
Click the key button next to the "New password" field. This will open the password generator.
It generates a password for you, but you can edit it or even type in your own password, and it'll give you an estimate of how strong it is.
Drag the password into the text entry field. (You can copy and paste it if you're not concerned about clipboard managers storing it, or clipboard-sniffing malware, but drag-and-dropping isn't any harder anyway.)


You can actually drag and drop text like this in almost any app! You need to click and hold for a moment before you start to drag, or it'll think you're trying to select.





You can also do this in Keychain Access – just hit ⌘N to create a new keychain item and click the key button, and it shows the same password generator.