Good point. They should probably add a button there to change the game store, just like you can change the install location.
On a side note - DId the automatic discovery not work for you? I am the author of that extension, and it should be detecting the install location automatically for the EA version from the Windows Registry. You might need to run the game once to get those registry entries, though.
You can always select "Stop Managing" there, run the game once, and then add the game in Vortex again.