Move: select Move, drag the coloured arrows, release the mouse, then press Lock item.
Snap: items within 35 mm of a wall or the floor snap flush. Move past that zone to keep a gap.
Keyboard: arrow keys move 50 mm, Shift + arrows move 250 mm, Enter locks or unlocks.
Rotate: select Rotate or use 90 deg. Locked items stay fixed.
Hide: temporarily remove this item from the scene and clash checks.