I do copyright like this (copy of the back of my title page):
Copyright © 2020 Cathleen Townsend
All rights reserved.
Published by Phoenix Flight Press
This book is a work of fiction. Names, characters, places, and incidents are either a product of the author’s imagination or are used fictitiously. Any resemblance to actual events or locales or persons, living or dead, is entirely coincidental.
Cover art by Deranged Doctor Design
My understanding is that at least in the US, your intellectual property is protected under copyright laws as soon as it's finished. What you're doing on the back of your title page is merely declaring it.
Trademark, OTOH, requires a registration process and fees, and they aren't cheap.
I am not a lawyer, but I believe the difference between the two is something like: Copyright makes sure you can continue to use your own ideas. Plagiarism of copyright-protected material is illegal. Trademark registers a certain specific idea, and only the person/entity with the trademark can use it. That explains the whole bit with Prince (the pop star). He became The Artist Formerly Known as Prince, not because he was pretentious, but because his record label had trademarked his name, and once he left them, he couldn't use it anymore.
I can't tell you much more about trademarking because I haven't done it. Most authors settle for copyright.