Responsive design issue - Edits in mobile + tablet affecting all viewports

[micgrace]

I know that when you make changes in a certain viewport, it only makes edits in that screen size and any viewport that is smaller. However, when I make edits in the tablet view, it's also making those edits on desktop and mobile, and when I make mobile edits, it's affecting all viewports. I'm pretty new to this, and don't really know what to do?

Here are my breakpoints:
Mobile - 767 px
Tablet - 1024 px

If anyone can help, I would greatly appreciate it