Final answer:
The word 'steered' conveys a sense of control and expertise in Jack's handling of the computer set-up, underscoring his proficiency with technology.
Step-by-step explanation:
The effect of the word "steered" as it is used in the sentences "Jack had it assembled, plugged in and switched on in under five minutes. He steered the computer through its set-up." suggests a sense of control and expertise. Similar to steering a vehicle, Jack is guiding the computer through its initial set-up process confidently and with precision. This word choice emphasizes the ease and skill with which Jack interacts with technology, suggesting he is adept at managing electronic devices.