Screenshot looks like the Window/Full Screen option in display settings has been set to Windowed, try setting as Full Screen.
The posted ini file is before the changes for the screenshot right?.. you want the x & y positions for dmd and backglass = 0, they're a relative position on the screen so by having them offset you're moving them - potentially off screen. Might not fix the problem with the backglass screen not appearing on correct screen, i know on my set up windows has screens 2 & 3 in the reverse order to how i use them in pinballx (from memory they used to match but changing a screen caused windows to change numbers but pinballx didn't, so they're now just out of sync). If you get back to dmd and playfield correct but backglass on wrong screen try all other screen number options in the backglass drop down.