I have 2 STM32F746 Discovery boards connected to my dev system. When I go to debug, VisualGDB does not ask me which STLink to use for debug. However when I am working on my laptop with the same project files, VisualGDB does ask me which STLink I want to use for debug.
How do I reset my dev box setup so that it asks me which STLink to use for debug?
VisualGDB would normally remember the USB serial number of the ST-Link you selected in the wizard/project properties and automatically select it next time. It will only show the selection dialog if more than 1 ST-Link is found and none of the found instances has a matching serial number.
If you want to select a specific ST-Link instance, simply pick it on the Debug Settings page of VisualGDB Project Properties (or manually change the serial number stored in the .vgdbsettings file to an invalid value to trigger the selection dialog).