Mobile View isn't Working

I’ve been trying to fix the mobile view in website for weeks. On desktop view, I have two columns side by side on some of my sites, but when you switch to mobile view, the columns don’t crop like they should. They’ll stack on top of each other, but part of them hangs off the screen. How do I fix this? I’ve tried meta name codes, css regarding the min-width, device-width, and others.
(Side Note: I’m not a coder, nor do I have much experience with it. Everything I’ve used is what I’ve found from Google and whatnot)

If its the front end, it will be theme related and dependant on what theme(s) your sites are using.