there is no application (it's built/hooked into the driver or something).  There is some kind of driver from Synaptic involved,  There likely is both a driver, which you can check in Device Manager, and an application that you would see in Apps & features. My system is just a little older than yours, also with Synaptics touchpad, and I have both driver and app. The point of uninstalling both is to start clean to see if Windows Update will provide what you need.  If that doesn't work, you could again uninstall both driver and app, then install the Win10 touchpad package from Dell:[URL] that Dell advises: "It is recommended that you install the Intel serial IO driver from Chipset category before installing the touchpad driver."    
I have tested and tested and here is the problem.  W10 UPDATE kb5016688: blows away Touchpad settings option.  I get this far and end up with a dead button (red). [IMAGE] and the touchpad ICON disappears from Taskbar.  ALL indications are the driver is correct and functioning, the hardware is functioning ... but the actual "desktop utility/feature" cannot be accessed and the touchpad will not scroll. I am sure it is the update because before, the utility was there and it worked.  I'm going to attempt to uninstall that update (it is optional) but I'm hoping for a fix ... or to at least warn other users.  Comments, tips etc appreciated in advance.
Inspiron 3521 W0 Pro UPDATE blows away Touchpad settings utility