Howdy @Rpatten and welcome to the community 
I know it can be frustrating to learn a new platform, but I’m sure once you get the hang of it you’ll find that it’s much more flexible than Squarespace.
To piggy-back on what @memetican said — since your project includes the 3 additional larger breakpoints, you’ll want to make sure all your initial design style changes happen within the base breakpoint (the center one with the star):
As you get smaller in viewport size, the changes cascade down, but as you go larger from that breakpoint the changes will cascade up. Essentially you’ll work outward from that point — probably first adding the styles for smaller screens and then going back to the first breakpoint on the left of the base size and working up from there.
The Webflow University has a great tutorial on the subject here, but I’ve also touched on this process in an older thread that you can check out here. Both resources should help give you a better idea of how best to go about making changes for different screen sizes without any styling surprises.
Hopefully that helps but don’t hesitate to reach out if you’re still running into issues 