Having 3 Monitors with a notebook using Windows 10, and easily finding / controlling the mouse.
I'm using a HP Zbook 4 connected to a Thunderbolt 3. There are two additional monitors connected to the Thunderbolt. One 60" LG monitor - connected with HDMI cable / audio connected by RCA cable (red/white) 2 into 1 connector, and one Princeton monitor VL1916 / 19in / SXGA / 1280 x 1024 - connected with VGA cable (no audio cable connection).
After considerable effort getting that Thunderbolt docking station to be recognized by Windows 10 Pro and the HP notebook, getting the three separate monitors working was a simple task. And making the mouse so it doesn't get lost and is easily managed was also an easy task. Note: getting that docking station to work finally came together once a "Display Link" icon showed-up with the other taskbar icons.
Using the built-in Windows, Display Settings, the notebook's own monitor gets assigned as Monitor 1. The LG monitor assigned to Monitor 2, and the Princeton monitor assigned to Monitor 3. And of course, these monitors are setup to "Extend desktop to this display".
Inside the Display Settings window, the monitors get arranged with Monitor 1 on the left, and Monitors 2 & 3 (in that order) stacked next to Monitor 1 on the right.
Even though this does not capture or keep a mouse cursor within a single monitor, this does allow for keeping the mouse under predictable control and the mouse never gets lost.
This setting allows for moving the mouse across the notebook's screen (left to rightward) and then either moving upward to access Monitor 2, or moving across the notebook screen and then moving downward to access Monitor 3 screen. The mouse never needs shaking or moving around to find a lost mouse.
I've been using dual monitors for more than 20 years. This is the first chance using 3 monitors. And having 3 screens is absolutely a wonderful thing. I'll never go back to using dual monitors.
A screen print of the Windows, Display Settings, is shown below: