‘A novelist is like a film director.’

A novelist is like a film director. It is not enough to say: in this scene such-and-such happens to so-and-so. The novelist must decide how to portray such events happening. As a writer, it is your job to decide where to position your camera so that you have a viewpoint that works with your story.

Experiment with this by taking a passage from a favourite novel and rewriting it. Change the viewpoint and the tense. Assess the impact of the change. And do the same with a piece of your own writing.