Few things in the Go4 app are simply annoying and DJI doesn't care to fix them even after so many updates.
I find the disappearance of the Histogram most annoying. Every time we restart the app, we have to go to settings and turn on the Histogram again. Everything else like shutter speed, white balance, sd card memory etc. remains on the screen. Even the manual settings remain the same as we had set last time.
Another problem is the AE lock. When we tap in the middle of the screen, a yellow padlock icon should appear and tapping on it should lock/unlock the exposure. However, I have found that it only appears in photo mode or when you had just switched from photo to video mode. So when you are in the middle of a video recording in Auto exposure mode and you want to lock the exposure at a particular point, it simply doesn't work. Thankfully, there is a way to overcome this - set one of the customisable buttons to AE lock/unlock.