Bring custom fields back to 1Password 8

I understand that you can add fields, but I want to modify "username" and "password" in a login!

I the password field type for both my username and password to randomize both of them for extra obscurity.

Why can I not rename these fields in 1Password 8

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1Password Version: 8.7.1
Extension Version: Not Provided
OS Version: 12.4
Browser:_ Safari