Resizing Finder Icons/Making Windows Larger with Trackpad

I'm accidentally doing something with my trackpad that makes all the icons on my finder desktop larger/smaller. I then have to go to view and resize the icons back to what they were, but the never end up exactly where they were before.

I know I'm inadvertantly doing some trackpad shortcut that's supposed to be helpful but I find immensly irritating. (Some clicking dragging motion or one of my other fingers gets too close to the trackpad when I'm dragging?) I also somehow sometimes make my Safari windows larger doing what I assume is the same accidental motion on my trackpad. How do I turn this feature off or at least lock the size of the icons on my desktop?