Hey! Sorry you're running into this. I previously had it automatically move windows back on screen when a display was disconnected, but a related issue caused me to default to turning that off. This will be fixed in the next update (0.8.13) which will be out soon.
In the meantime if you're the type to mess around with settings files you're welcome to navigate to `%AppData\MiniMeters`, open `settings.json` and add or set `"reposition_offscreen_windows" to true` Alternatively feel free to reach out on the MiniMeters Discord and I can help you modify the file, or modify it and send it back to you. Sorry for the inconvenience.