Actually I think there is ... I accidentally discovered it ....
I normally have my computers lined up in the center for Primary, far right center and far left center for 2 other computers ...
I found that when I was doing some online work and sharing control people would run off the screen ... etc ... you all know what I mean ...
so I moved my 2 secondary computers to the upper left and upper right grids and .... my primary mouse stays on my primary screen .... UNTIL I move the secondary computers back to their center left and center right spots on the grid ...
would be interested to know if anyone else tries this and it works ... or if I am just lucky (then I should buy a lottery ticket) or just special ... hahah
good luck to all . Dave M