This sounds very familiar...
I often have the luxury of using 2 or even 3 monitors while developing, one would typically show Excel itself, the other the VBE window (and email or browser on MrExcel on the 3rd
)
The userforms however appear either over the Excel window, or over the VBE window, depending from where I start the macro. There also seems to be some memory effect like you describe as well... start a macro on screen 1, userform will show on screen 1, move Excel to screen 2, stop the macro, start the macro again, userform will again open on screen 1...
I have yet to find the system and logic behind it though
Excel isn't too good with handling multi-monitor setups, I like to use them during developing, afterwards, when using the application without the VBE open, and using only 1 monitor, it usually (
) goes well...
Sorry I couldn't give any detailed solutions...