Any way to change the number designation of monitors?

I use a Toshiba Dynadock to connect to my monitor from whichever of my 3 NUC's I am using. 2 are Win 7 Pro machines and they work fine, but my new Win 10 Pro (19042.928) pc won't play nice at all. After hours of fiddling and searching, I'm pretty sure I know what the problem is, but ... I've found no way to fix it. And the worst part is, I can't know if that IS the problem, until I can fix it.

Whether I have one or two monitors physically connect to the PC (one directly, the other via the Dynadock), it shows two displays (in settings) and the Dynadock monitor is labeled #2. I've made it my primary monitor, tried show only on 2 ... basically every setting available. But as soon as I cold boot, I lose the Dynadock monitor as my active desktop (even if it's the only monitor connected), as the active desktop reverts to Monitor #1. So I need to make the Dynadock monitor #1. I've found no way to do this though. (I did find one method, using the registry to force it to recognize on reboot, but it didn't work for me)

So, what I'm looking for is a way to change the numerical designation of the displays shown in Display Settings.

I've rearranged the displays, and in every configuration possible. I've installed, uninstalled, cleaned and reinstalled the drivers numerous times. I've tried the registry fix, it didn't work.

The Dynadock is a USB powered hub with display and audio (5.1). The monitor connects to the dock, and then the dock to the PC via USB 3.0 cable. Without a monitor connected through the PC HDMI or Display Port, I get USB connectivity (ext drives, mic, CD/DVD player, wireless mouse and keyboard) and audio, but all I get from the monitor is a black screen with the cursor visible. The only way I've found to get the active desktop on the Dynadock connected monitor is to have a second monitor hooked directly to the PC for startup, and then switch the monitors in settings after windows has opened.

When you start up windows after a shutdown (cold boot), it defaults to monitor #1 for the active desktop ... even if it isn't connected to it. I'm okay if I do a restart, but not when I do a shutdown.

I've looked into disabling Fast Startup, but it doesn't show as an option (including unavailable options), through Control Panel. So I don't know what else I can do. I appreciate the suggestions, even if it doesn't sound like it. It never hurts to try something more than once when nothing else is working.

I should note, I live on a 32ft sailboat, so don't have much in the way of room to put stuff. That's why I use NUC's and the Dynadock. I have a 32 bit and 64 bit 5th gen NUC running Win 7 Pro (32 for legacy programs) and now the Win 10, plus NAS on a wired network. All the PC's and NAS are at one end of the boat, while the Dynadock w/monitor, speakers, ext drives and mouse/keyboard are at the other end. So instead of having one PC with multiple monitors, I have one monitor with multiple PC's.

I'll keep playing with it, but can't say I have much hope. It seems this has to do with 'enhanced support' for multiple monitors by both MS and Displaylink (the Dynadock). Nobody on Displaylink has even responded, and nothing I've found on the web really addresses my situation. 'Preciate the help though. I'll let you know if I figure it out.