I didn't do it, did I? I didn't alter the settings. I saw something on the rocker button that I had not noticed before. By pressing it, I was directly led to brightness exposure number settings. Oh, as well there are vivid settings and other settings. The exposure setting was on -0.3. No wonder so many of my photos are so dark. How could I have not noticed these settings before?
Stupid old men dealing with tech stuffs.