Where is adjustment screw for headlights on 2008 impalla

SOURCE: 1997 Tahoe Headlight Adjustment

the two large screws on top are to remove light totally.You need to look down the holes with a flash light to see the adjustments.

SOURCE: Headlight adjustment

If you park in front of a garage door or building you can line up the lights .right behind the headlight you will see two shafts sticking up just below the support the headlights are attached to. One will adjust lights up &down the other one will adjust side to side.

SOURCE: Passenger Low Beam Headlight needs replacement!!!

You could remove the air filter cover and then you will be able to reach the bulb.

SOURCE: one headlight dimmer than the other

bad earth,Run a new earth wire from the drivers side head light.

SOURCE: How to change the headlight bulb on the passenger

Step 1 - Raise the hood and remove the 4 push-in retainers that go along the top of the front grille. These are each two part retainers - remove both parts by prying with a small screwdriver. Nothing comes off here - this just makes the grille loose for maneuvering the headlight assembly around to get it in and out.
Step 2 - Remove the "bow tie" trim piece that runs from headlight to headlight thru the middle of the front grille - it is cheap plastic so do this carefully (mine looks like chrome with the Chevy 'bow tie' in the center). To do this, use a flat-bladed screwdriver and a rag (to protect the headlight). This trim part comes off - I started at the driver's side and work toward the passenger side. Place the rag below the trim on the headlight. Carefully pry up on the trim piece with the screwdriver and work the trim with your fingers until it pops out of the headlight assembly catch. There are lock tabs on both the top and bottom of this trim piece when you get to the grille area. Work your way down the trim piece by prying wherever you locate a tab and protecting with the rag as you go until the "bow tie" trim piece comes off. The headlight assembly catches are the tightest. Set it off to the side so you don't step on it or scratch it.
Step 3 - Unbolt the light assembly. There are two hex-headed screws on top and one 10MM down inside (towards the center of the car). Remove these 3 bolts.
Step 4 - Remove the assembly - There are 2 guide tabs in the lower outside part of the light assembly (opposite the 10MM screw). Wiggle the assembly while pulling out (forward). When the tabs clear, lift up on the headlight and it should be easy to work the rest of the way out to gain access to the headlamp.

Step 5 - remove and replace the bulb - it is halogen so you DO NOT touch it with your fingers because the finger oil will cause a hot spot and the bulb will burn out fast. Handle the new bulb with a clean cloth - a clean sock works well.