You will want to do this in the camera OSD.. I am not sure the camera you are using but if it has one you can normally get to it by using the PTZ menu of the DVR. If your camera is TVI and using UTC, This is also where you can change the cameras ability to be PAL and NTSC in side the OSD of the camera setup camera by camera. Your DVR should have setup for your type out of the gate and normally the cameras when added would normally be setup for the same mode however in some cameras you will need to do it again in the cameras OSD.. If you don't have UTC and the camera has a Toggle in the camera or on the Wires then you will need to gain your access to the OSD that way. But most newer camera have UTC access. Here is 3 pictures one showing OSD for a 2017 might be 2016 can't remember right now TVI camera that I am accessing the OSD on my Amcrest 8mp Ai DVR and sure my camera has Toggle in the camera but I can also access the camera over PTZ without any RS485 wires running because the camera works over UTC as well..
If you don't know how to access your camera and if it does offer OSD then bring up PTZ menu, put in 95 and press go like you are trying to go to the Preset some cameras you have to press the add button either way you might need to try both. Then some cameras you can access OSD by pressing the IRIS Open/Close that isn't how mine works because my camera has iris function that will just change the iris but for cameras without it that can open the OSD.. Then in the OSD if you don't have the OK button then you will have to try iris for my camera when in OSD it is focus buttons if I didn't use the OK button.. IF you have never been in the OSD it will take a little getting used to, then for me I have many different cameras some more features then others so I have to fumble around sometimes to get it right lol.