I have not read all the posts (thoroughly), but here is something to consider.
MS have allowed in most versions of windows for the user to change the DPI setting away from normal (make the text bigger).
They(MS) should be shot for offering this.
You could explore using your program on both a W10 and a W7 PC which has the setting at normal, where it belongs (The way God intended).

Rob
PS I will get flamed by some who use that setting to make things easier to read.
To those flamers, "I say solve that problem properly" -
- Get a bigger monitor
or
- Use a decent screen magnifier that with one keystroke can double the size of everything, and another key stroke to switch back