Alright, I'm going to be showing you how to do this, very quickly.

Step 1, Open an *instance of the new launcher*. Image

Step 2, Customize settings, and click *play*. Image

Step 3, Open *Task Manager*. (Ctrl + Shift + Esc) Image

Step 4, Click *More details*. Image

Step 5, Find *Minecraft launcher** and select it.* Image

Step 6, Click *End Task*** Image

Step 7, Open a *new instance of the launcher** and play.*

• Repeat for each new instance of Minecraft you'd like.

GIF