Using multiple monitors

Hi folks,

there are multiple threads on using more than one monitor, but there is one problem I cannot find the answer to: When I undock and move lets say four panels and when I am done press Alt + ENTER again, I find two of the panels on the primary monitor and the two others on the secondary even though I had moved all four to the secondary when they were windowed and undocked.

Any idea what could be done to make the panels more "sticky"?

Best,

Holger