My design view doesn't look the same as when I view the website

I am VERY new to this and doing it as a favor for a friend. I am sure there are lots of things wrong on my site that I need to fix so any help would be amazing. However, I can’t seem to get things to line up correctly and look correct on my designer and then my actual website view.

Other issues I have are that anytime I change the mobile views it also changes the desktop view. How do I stop this?