Generally, we use:
- at for a POINT
- in for an ENCLOSED SPACE
- on for a SURFACE
- I live on the 7th floor at 21 Oxford Street in London.
- The shop is at the end of the street.
- I have a meeting in New York.
- There was a “no smoking” sign on the wall.
Look at these standard expressions:
|at home/work/schoolat college
at the bottom
|in the car/taxi/boatin the newspaper
in the sky
|on a bus/train/plain/shipon television/radio
on the left/right