When can an author use slang/figurative language or speak directly to the reader?

A. When writing to persuade
B. When writing to inform

i’m writing a memoir and i’ve been given the great suggestion of placing a ‘sub-narrative’ within some of the chapters – sort of, what was going on with me in the grand scheme of things.

i was wondering how to format this so that it is very obvious we are stepping out the of story.

firstly is a change in font from serif to sans workable? i also use dashes for a scene change. was thinking of using a different scene-changer too.

here’s a (shortened) example:

university – or what’s known as ‘uni’ in australia – were some of the best days of my life. where else do you get to potter around in a great location, have very little responsibility, learn lots of things, do lots of things and walk out four years later with a bonus – a degree!

with my university years i had immersed myself into community of intelligent ambitious people. generally everyone had a confidence about themselves. they knew where they were going in life and weren’t threatened by others.

—–

next normal paragraph continues here…

(sorry couldn’t show the fonts in this comment field)

too much?

i literally just read the book and studied it for months so i could you, but i need to know where these questions are coming from. they are too general.

the climax is the highest peaking point of the movie it is mostly near the end of the movie where the main characters point of view changes. it is the most excting action part of the movie