Hey Leonardo! I’m sorry to hear you’re frustrated!
Thankfully, I have a solution that you can try and let me know if it solves the problem.
When you’re working in the page builder in the desktop version and you don’t want changes to apply to your mobile version, hold down the command key if you’re working on a Mac. If you’re working on PC, hold down the Control key.
Here’s some documentation to help you out as well (scroll to the section titled Moving elements between page sections and unparenting nested elements)