Even in 2019 macOS fails to preserve my monitor layout. I wrote a tool called displayplacer that lets describe your monitor layout as a terminal command. I then use BetterTouchTool to execute these profiles via hotkeys. It solved the same problem for me of using the same model monitor at work (in portrait mode) as at home (in landscape mode).
For example, ...
Now as the ForkLift V3 came out, the new command should be:
defaults write -g NSFileViewer -string com.binarynights.ForkLift-3
At the same time, if you like to restore Finder to be the default file manager again, use:
defaults delete -g NSFileViewer
While it may be a bit cumbersome, I use the Rectangular Selection Tool, then go to a corner of the image that suits your coordinate system (top-left in some cases, bottom-left in others) and stretch the rectangle to the desired position.
The size of the rectangle shown in the tooltip will be your position.
Zooming in helps to be more precise.
First item, you get two sessions max. If you are struggling with the first or second session, then the issue could be your VNC software that connects to the mac isn’t following Apple’s conventions to allow the second session to start. Since you didn’t specify versions of software you use on the connecting side, I’ll guess and give general advice.
There is ...
On my setup (external PC-style keyboard, Karabiner Elements, and single application I care about), I remapped a PC Menu key (Karabiner sees it as "application") to Keypad Numlock.
The application (CLion) has hotkey remapping ability and supports context menu for focused controls, so I mapped the key in the application.