I cannot get “System Preferences” to open on my external monitor instead of my broken laptop screen.

My laptop screen is broken. I have an external monitor and recently switched cables for it, and with this new cable, I cannot get Displays to open up on my monitor screen, only my laptop screen. The screen is extending instead of mirroring.

I tried to clamshell, and it gets Displays onto the screen, but the option to change my Dell monitor to the main display vanishes, and I see no extend/mirror options.

I tried a third display with my TV, but that seems to set up a new and separate relationship between the screens, so when I put the Dell as my main display, once I DC the TV it goes back to extending my laptop screen and Displays vanishes again.