Hello,
Sorry to hear you are having issues. If you are not yet on Fences 5.81 Beta, please download and install it and Reboot. And for multi-monitor setup please use the last option "Store my layout on a per-monitor-configuration basis". This will save your layout. Use the blue link "Adjust displays" to change your layout between monitors.
Thank you.
Basj,
Stardock Community Assistant.