You need to both raise them to get the woofer's wide beam of dispertion further above the floor, and tilt them back to project the tweeter's narrow sound beam up to your seated ear height.
This has the advantage of altering the angle of reflection off both the floor and ceiling, and if you adjust their toe-in, that alters the angles of reflections off the side walls
https://www.audiogon.com/systems/11516