On the right there are the seeds that are in seed tray of your game. When you want to save some seeds, select them, click on the 3 arrows in the middle (<<<) and the seeds will go to the left side. They disapear from the game and are on the "virtual tray"!
Then "save change" and QUIT the VST before going to your game. If you want to have some seeds in your game, quit the game before going to the VST and you may chose some seeds of the left part and put it to the right part (>>>).
(ps: the seeds that are in the tray of the main screen can't be seen in the VST)