I am using Windows 8.1 on my laptop, which has a 15.6" screen with resolution 1366x768. I measured the screen with a ruler and calculated its DPI, which is 101. Therefore, I have set the scaling to 105%. However, when I change to an external monitor, which is a huge one with resolution 1920x1080 and DPI 93, I need to change the scaling to 97% but when I change the DPI back and forth, my font sizes have get resetted.

I prefer using font sizes 14 on my title bars, message boxes and icons and font sizes 13 on my palette titles, menus and tooltips. However, as my laptop screen is too small, in order to make my apps fit on screen, I use font sizes 12 on my title bars, message boxes and icons and font sizes 11 on my palette titles, menus and tooltips. I don't know why I can't resize the window to make it larger than my screen in Windows (but it is possible in Kubuntu), therefore, some parts of my apps cannot be shown with my preferred font size.

I have tried changing both the DPI and the font size by using .reg files. Before switching to my laptop screen, I apply the following:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Control Panel\Desktop]
"LogPixels"=dword:00000065

[HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics]
"CaptionFont"=hex:ef,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,bc,02,00,00,\
  00,00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"SmCaptionFont"=hex:f0,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,bc,02,00,\
  00,00,00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"MenuFont"=hex:f0,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,90,01,00,00,00,\
  00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"StatusFont"=hex:f0,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,90,01,00,00,\
  00,00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"MessageFont"=hex:ef,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,90,01,00,00,\
  00,00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"IconFont"=hex:ef,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,90,01,00,00,00,\
  00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"AppliedDPI"=dword:00000065

Before switching to my external display, I apply this:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Control Panel\Desktop]
"LogPixels"=dword:0000005d

[HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics]
"CaptionFont"=hex:ed,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,bc,02,00,00,\
  00,00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"SmCaptionFont"=hex:ee,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,bc,02,00,\
  00,00,00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"MenuFont"=hex:ef,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,90,01,00,00,00,\
  00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"StatusFont"=hex:ef,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,90,01,00,00,\
  00,00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"MessageFont"=hex:ed,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,90,01,00,00,\
  00,00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"IconFont"=hex:ed,ff,ff,ff,00,00,00,00,00,00,00,00,00,00,00,00,90,01,00,00,00,\
  00,00,01,00,00,05,00,53,00,65,00,67,00,6f,00,65,00,20,00,55,00,49,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"AppliedDPI"=dword:0000005d

I expect after applying the file, the DPI settings and the font sizes take effect at the next sign in. However, on my laptop screen, after I applied the file, signed out and in, the DPI setting changed, but the font sizes were resetted to tiny, and I had to apply the same file, signed out and in again to get the correct font size. The situation is even worse on my external monitor. After I applied the file, signed out and in, both the DPI setting and the font sizes were resetted to their default values, which were 96 DPI (the physical DPI as measured by dividing the resolution by the physical size is 93) and font size 9, which is totally unacceptable. How can I write the .reg files such that the settings can be correctly applied with a single sign in?