The Amend Commit checkbox should not be hidden in a menu.

1) It's hidden and it's multiple steps to choose it
2) There is no on-screen indication of when it is turned on
3) If you subsequently turn it off, there is no visible indication at all that it has been turned off (e.g., the overridden commit message does not revert).
4) It's hard to find for new users.

I cannot think of any rationale for hiding this option. In fact, why hide anything in that menu?