How to change the emulator?

Question

android studio

All shalom! How to change default emulator in activity_main? Of course, I don’t know how it’s called correctly, but I’ll explain it differently, when I create a project, I choose a template, let’s say empty and a layout is created, it has two design buttons, text, I click on design and it shows a window like a phone, and here’s how I change it another?