Why do i have to press my shutter release button twice to take a picture on the Nikon d850 and how to i change this?

My Nikon D850 is fairly new, and I'm trying to set it up. For some reason, when i try to take a picture, it makes me press it twice to take it. The first time the shutter closes, then the second time it opens. I have looked everywhere in the menu to change this so I only need to press it once to take a picture, but can't find anything. How do I change this?

Continuous shutter. At least on a canon.can't be much different

Look up "Long Time-Exposures" in your manual. In manual mode you can set the shutter to "Bulb" mode which keeps the shutter open as long as you keep the shutter release button pressed. If you have it set to "Time" (time exposure) mode then the shutter opens when you press the shutter release button and closes when you press it a section time.

From page 133 of manual, "Time (- -): Start the exposure by using the shutter-release button on the camera, the optional remote cord, or wireless remote controller. The shutter remains open until the button is pressed a second time."