Sit at / on / in front of the computer?

Dear teachers,

I am writing a diary about what I was doing for the past few days.
Here are the sentences that I am not sure which is the best in grammar:

  1. I was sitting at the computer doing my assignment until midnight
  2. I was sitting on the computer doing my assignment until midnight
  3. I was sitting in front of the computer doing my assignment until midnight
  4. I was sitting in the front of the computer doing my assignment until midnight
    Could you help please, teachers.
    Could you also suggest your sentences if possible, teachers?

Thank you

Kitty

Where are you living now? Are you a real Australian? I can’t believe that an Australian can ask a question regarding ways of expression. It’s we that have to learn from you. Though, I think you should use in front of. Sometimes, we can still even use informal words in our literature assignments, not to mention a diary. It’s simply because we don’t know every word whether it’s formal or not.

Most people I know would probably use the first sentence, but number 3 seems fine to me as well. Number 2 makes it sound as if you were sitting on top of the computer and number 4 makes it sound as if you were sitting inside the front of computer.

However, if you are writing for something in Australia I may be wrong, as there could be regional differences in how people would express what you are trying to say.

EDITED: Whoops, I read the number wrong! Sorry.

(1) and (3) are correct. However, (2) is also correct if you were really sitting on the computer and doing your assignment (meaning, to use the computer as a seat). Ha ha.