Why is my Apple Watch Passcode section greyed out?

Everything under the Passcode section is greyed out except Turn Passcode On and Wrist Detection on my Apple Watch Series 10 paired with an iPhone 16, which an organization does not manage. I want to set a passcode with more than four digits. I also have an Apple Watch Series 7, which was already set up with a six-digit passcode when I paired it to this iPhone 16, as it was the previous watch I used with my iPhone 12. How do I get access to everything in the Passcode section?

[Re-Titled by Moderator]