Opening external software and mmcs in RDM

I am trying to use some software like Notepadd++, Hyena and PrimalScript in RDM instead of having multiple windows open. I have been successful in open them and other mmcs like Group Policy Management console and Active Directory Users and Computers in RDM. The only issue I am having is that when I open them on my 24" monitor then open in the entire screen but if I open or go to another session and then go back to the first open session the window is not expanded across the entire screen anymore and it's only showing in half the window. I have attached examples of how it looks when the session first opens and then what it looks like after going back to an open session. Is there any way to force it to always use the maximized space of the screen?