To adjust the AheadSet, make sure that the stem bolt is loose. Snug the top Allen bolt just enough to remove play without introducing any tightness. Keep in mind that this is not the bolt that holds the stem onto the steerer, and it shouldn't require excessive torque. In fact, the top cap is designed to break if the bolt is tightened too much. (If moderate tightening doesn't remove play, consult shop personnel.) Turn the fork slowly and push and pull it to check the adjustment.
When it's right, align the stem and tighten it's bolt to lock it. Tighten the cable hanger.
On the Santanas, there are 2 spacers below the stem. If you wish to lower the stem, remove the stem and 1 or 2 spacers. Replace the stem and place the removed spacers above the stem and tighten as above. If desired, the excess steerer tube can be cut off to eliminate the need for spacers, but that is a permanent change which would prevent you (or anyone else) from being able to raise the stem in the future.