I have a Dell Latitude 5300, but I think this is a generic Dell touchpad question.  If I'm using the touchpad to scroll through a document using a scrollbar, something (probably a driver) decides that I want different behavior in the middle of the touchpad than at the edges.  So, if I'm scrolling up and down, I grab the thumb/elevator by double-tap and hold, then move the elevator by moving my finger across the touchpad.  I get smooth, expected motion as I drag my finger across the touchpad.  So far so good - this is just like using a mouse to do the same thing. 

However, when I get my finger close to the top or bottom of the touchpad, I get completely different behavior.  Now, suddenly the elevator is moving up or down on its own, without me moving my finger at all.  If I'm scrolling up, I'm suddenly flying up the page without much control.  If I'm scrolling down, ditto but going down.  

Is there some way to shut that behavior off?  I would rather have to pick up my finger and reattach to the elevator, than have it suddenly decide on its own that I'm near the top/bottom and radically change behavior.  But I can't find any way to shut that off.  It doesn't show up in the windows touchpad settings, and I can't find any Dell settings app to use to shut it off.  It doesn't seem to show up on mouse settings either.