I'm working with 2 different computers and one main 2K monitor, so I use a switcher hub to jump from displaying one computer to displaying the other. The issue us that my MBP, every time I switch away from it in the main display, gathers everything onto its default screen: windows, dock, desktop icons, and it changes the resolution, so that when I switch back to it on the main 2K display it un-gathers everything, sends it back to the main display, but now on the MBP's screen the image looks horrible: pixelated and blurry, so that I need to click on CMD + Lower Brightness 2 times, to switch back and forth from main to secondary display on the MBP for the resolution to go back to what it should be. (Not to mention it leaves an unused screen space at the bottom where the dock used to be.)
This doesn't happen when I simply turn off my 2K monitor. In that case, the MBP remains as just a secondary monitor. Which is why I'm asking this, assuming that there must be a way of forcing my MBP to always be a secondary monitor, no matter what—even if that means that whatever is on my main display is entirely un-reachable if the main display is now showing my other computer.