I used to drag files easily from one location to another in Finder on my old MacBook Pro with an older operating system. (using thumb and one finger on trackpad). Now I have to work really hard at it, and usually it opens the window i'm attempting to select, instead of letting me select and move it. After trying 4 or 5 times (and wearing out my arm muscles), I can get it. I'm sure there's a simpler way.
I tried to find preferences for this kind of thing, but under apple preferences, mouse, there is nothing (since I use a trackpad and not a mouse), and under trackpad it doesn't give choices for setting taps for dragging, or anything else related.