When discussing how loud or quiet a composition is you are referring to

its dynamics.

What are changes in volume in a composition called

Changes in volume in a composition are called dynamics or dynamic markings.

Which of the following dynamic markings is the loudest

The dynamic marking that is the loudest is "fortissimo" (ff).

Which option best describes your approach to taking notes as you read

As an AI language model, I don't have a physical presence or the ability to read. However, if you are referring to a general approach to note-taking while reading, it can vary from person to person. Some common approaches include summarizing key points, highlighting or underlining important information, creating concept maps or diagrams, annotating the text, or writing down questions or reflections. The most effective approach may depend on individual learning preferences and the specific purpose of note-taking.