My question is about Image Viewer (not sure how it is called). When I double click an image it opens in my main monitor, but I want it to open in my second monitor. What should I do in the preferences so the images open in a specific position and don't rely on default settings
Move the viewer to where you want it to open, then close it. Next time it opens, it should be on the same screen.
(There is a bug with this which was just fixed in 12.27.2 beta, so you might want to install the beta if it doesn't work, but it usually isn't needed. The beta has proven stable so should be low-risk.)