How to change the background color of each page of multiple page form

Good night, how to change the background color when i change the page?

You can achieve this only if you will use the source code embed of the form.

User guide: How-to-get-the-Full-Source-Code-of-your-Form

You can assign a background color on style/format on each of the page section within the source code of the form.

Hope this help. Let us know if you need further assistance.