I hanged my new kitchen wall unit and tightened the 2 blocks inside to ensure the cabinet is level and vertical. However, the bottom is still very easy to tilt. I checked the old one which was fitted by other prof. it is solid. Do I have to screw the bottom down onto the wall as well? I did not see this in the old carboard.

Thanks

Make sure you have tightened it back to the wall fully. The bottom may pull out slightly, but once you've filled it with plates/tins/foodstuffs/ glasses, etc it won't move anyway.

sometimes i find when fitting wall cupboards the wall isnt straight,so i drill a hole through the hardboard near the bottom and insert a screw with a cup and just take up the slack enough to hold it back to the wall.
obviously checking for wires etc.

Yes, I screwed down at the bottom. They look better now. Thanks