asks: How do you change viewpoints in a multi-viewpoint novel?

There are a few ways to do this. The most important thing is to make sure it's absolutely clear to the reader whose viewpoint is currently active.

- An easy way to switch viewpoints when there are two main characters is to switch characters every time a new chapter starts. In other words, when it's time to switch viewpoints, you start a new chapter. It's okay to have short chapters. Rainbow Rowell does this in Eleanor & Park, and I enjoyed it a lot. I was never confused who was speaking, even though there were no chapter titles, because the chapters followed a pattern. Each new chapter meant a switch in point of view.

- If you don't like the idea of a switching point of view every time a new chapter starts, you can add a chapter title stating the name of the character who's narrating. This is also helpful when you have more than two points of view to juggle.

- Another popular method of switching viewpoints is an extra gap between paragraphs. Such gaps are often used to signify a new scene. They can also be used to switch to another character, so long as the wording makes it apparent who it is. Be sure to use the character's name in the first sentence.

It's best not to switch viewpoints too many times per scene, or the reader may get dizzy reading it. In my opinion, each main character should express their viewpoint once per scene. After switching away from their point of view, don't switch back again until the next scene.