Here you go, there should be 3 lines on your dji go 4 app screen when connected to the drone, click that and it will bring up the camera settings. I linked a video to show you what the menu looks like, and once you see that menu you will see the EV down at the bottem with a + and - and the little slider. You should be able to tap the - button a couple times and get the ev back to 0.0, which is normal.
Now also keep in mind, It also sounds like you are in M manual mode for your camera instead of A or auto. I highly recommend you fix the EV back to 0.0, and switch your spark back to AUTO mode, at least until you learn a bit more about exposure and how to set it manually. Because manual is just that, MANUAL meaning that every time you turn the drone, every time lighting conditions change just a little bit you have to remember to go into your settings while flying and edit them to look good. And since it sounds like you are still getting started to manual exposure, it would be extremely difficult for you to fly, remember to check your photo settings, and edit them on the fly while also avoiding obstacles and trying to get good shots. Once you learn a bit more about exposure and how shutter speed, aperture and ISO all relate to photo quality, then you can start going into M mode and having some fun.
So in conclusion, fix this EV issue, get back on auto mode, and enjoy flying!