If you search around the forums before you post, you can find quite a few complaints about the Pro Camera app seeming to give a yellow tint to photos. Sounds like a problem with the app that can easily be fixed. Hang in there.
It isn't a software problem because my Lumia updated last week and all apps, including the Camera app that comes with the phone, are doing yellow and low sharpness pictures.
I have tried many different apps and all of them change the original photo to a new yellow ugly photo after some seconds.