我的工作是教顾客怎样用电脑。Translate it into English.

Question

Please provide a better answer and explain it into English.
What is the difference among (1),(2),(3),and (4）？

1)My job duty is teach customer how do use computer.
2)My job duty is teach customer use computer.
3)My job duty is teach customer computer.
4)My job duty is teach customer using computer.

Answer 1

1) My job duty is to teach customer how to use computer
- Grammar mistake in the original sentence
2) My job duty is to teach customer using computer
- Grammar mistake, should add 'to' before 'teach' (Verb) "Verb-to-be format"
3) The meaning of the sentences doenst match with the Chinese statement. Also, the grammar is incorrect.
4) My job duty is to teach customers how to use computer.
- Again, verb-to-format

Answer 2

My job duty is to teach customers how to use computers.
My job duty is to teach customers using computers.