One tree on two computers

Using FTM2012, I have a tree on shared disk between two PCs. I usually use only the desktop with a large screen. I am now also using a laptop with smaller screen.

I have a problem sometimes when I close FTM, I see the screen closing the file, on the laptop and open on the desktop, maybe hours apart, and find FTM with the screen size of the laptop and I can use the Search option to connect to Ancestry but I cannot merge or change the parameters relating to the individual in the upper left panel of search. Doing this in the opposite direction also has the problem with search but screen size is max for laptop.

Anyone with experience or recommendations?

Thanks,
RON C
Laptop is XP x32 and desktop is win7 x64.

In this case, I must shut FTM on the desktop