This is actually a common problem with USB-C. It's not just the Surface Book. If you search online you will find the same problem in the forums of all the PC manufactures. USB-C is just a ****technology.
I would suggest that you use a Surface Dock with a surface active mini display port to HDMI adapter for each monitor you use. If you are only using one monitor and it has a display port connection you can also use a mini display port to display port cable.
You can also read my previous posts regarding external monitors with the Surface Book.