the purpose of QuickTerrain is that it is locked to a set position (to make it match with exporting track models). So you'll need to move the model itself inside 3D software.

Though you can also extend the room in the opposite direction (pressing the minus buttons on the room size) which will move the walls further away from the QuickTerrain

If you want to move the terrain around like a normal prop then you could also make it as a prop mod instead of QuickTerrain

👍🙂