Hi, pineapple_2910! Our "EOS 101" video series on YouTube teaches you what the exposure modes on your camera do and how you can take advantage of each one. While the information presented is intended for users of Canon EOS cameras, the PowerShot G series, which includes your PowerShot G7 X Mark III, has a lot in common with those cameras and you can easily apply those instructions accordingly to get similar results. Check it out HERE.
Hope this helps!