Problem:

Working on Windows 10, the default printer is changed when the application closes and the runtime is shut down.

For example: the default printer is set to PRINTER1.
The COBOL program sends a print to PRINTER2.
After the run, PRINTER2 becomes the new default printer.

This never happens on Windows 7, where the system settings remain unaltered.

Resolution:

This appears to be a "new feature" of Windows 10, rather than an issue within the ACUCOBOL-GT runtime.

Some versions of Windows 10 have a switch called "Let Windows manage my default printer". 
When turned ON, the last used printer will become the new default printer in the system. 

Here is a link that explains this "feature" and how to turn it off: 
http://www.tenforums.com/tutorials/26138-printer-turn-off-let-windows-10-manage-default-printer.html

Briefly speaking:

Open Settings -> Devices -> Printers & Scanners (on the left side)

On the right side there should be a section that says:

  "Let Windows manage my default printer"

with a switch that can be turned OFF to keep the default printer chosen by the end-user. 

SI 2872545