How to default Column entry in the second field to Incident ID for search and link within a tab.
Currently the only way to do this is via the Administrator role. Once you click on the Link button for that BO's tab and the Search dialog opens, you can select the field needed and then select Save Search as Default.
There are slight differences in how this works in 2014.x compared to latest 2016.1.1 in that 2014.x will require you select a valid value for the field. Example: If I want to use Status as the defaulted field, I have to select a value for status in order to Save Search as Default.
In 2016.1.1 you can actually enter a space in the value field and it will save, which is more truly a limiting to the field and not a field and value when the Link search first opens.
Again, the Save Search as Default has to be set as the Administrator role and then will be available for other roles that have access to that Link/Tab.