By Default, Vegas will perform a cut when clicking a take in the multi-cam mode (or pressing the camera # on the keyboard), and using the Ctrl-key as a modifier will tell it to perform a Cross-Fade instead of a cut.
Is there a way to change this behavior so that the default would be a cross-fade, and the modifier changes it to a cut?
No, but you can try the followig workaround. In the made videofile on one track 1. Change the first made default transition and copy that one 2. Select all to the last event 3. Copy event attributes with this selected