There are already wishlist items for this if you search the forums.
In the meantime, check out MSFS Pop Out Manager, works awesome. Remembers screen sizes, locations and pops them out automatically for you and puts them where you had them.
Must have for home cockpit builders using pop outs, I have 8 on the CRJ900 and this saves a TON of time.
Before this came around, we used PowerToys FancyZones.
It still works as well, but Pop Out Manager has more features.