Think about it this way: you've just appointed an auditor for your company. Now who decides how much to pay them? That's exactly what Section 142 answers — and it matters for both governance and exam marks.
Who fixes the remuneration? The short answer: the shareholders in a general meeting. This makes sense — the auditor is supposed to be independent and report to shareholders, so naturally the shareholders decide the pay. You cannot let the Board silently decide what to pay the auditor every year, because that creates a conflict of interest (an auditor whose pay depends on the management's goodwill is unlikely to be truly independent). There is one clean exception: when the Board appoints the first auditor (which it is allowed to do under Section 139(6) before the first AGM), the Board can also fix that first auditor's remuneration. After that, it goes back to the general meeting.
What counts as 'remuneration'? This is the part students miss. Remuneration under Section 142 is broader than just the audit fee. It includes: (a) the audit fee itself, and (b) any expenses the auditor incurs while doing the audit — travel to branch offices, hotel stays during a factory visit, printing costs, etc. — and (c) any facility extended to the auditor (say, the company provides a company car for site visits). However, it excludes fees paid for any other service the auditor renders — for example, if the same CA firm is also doing GST consultation or tax filing for the company, that fee is NOT part of Section 142 remuneration. That separate fee is governed by other arrangements and must be disclosed separately in the financial statements. This distinction is frequently tested as a 4-mark theory question in CA Inter Auditing.