When my F/O questions my authority
Your authority to do what?
Disregard the SOPs?
Get the operation into a potentially embarrassing (or indefensible at an inquiry) situation?
Put the aircraft in danger?
Part of the job of the FO is to watch the Captain's blind spots. Second pair of eyes and all that. One of the more difficult duties is to occasionally rein him in when he starts misbehaving. And yes, some Captains do.
Of course, there are plenty of good reasons to deviate from the SOPs from time to time. However, I know that there are some less responsible Capts who do so to show off, prove a point, or just do it because they can. This can quickly distract the FO, make his life difficult, and prevent him effectively functioning as a useful part of the crew.
People will ask, airbus-commander, if you're ex-military. In fact, with the attitude that seems to be on show here, I strongly suspect you're not.
All the best.
CC