Set up recurring report templates

Before I hand these templates to Jamie in finance and the three business unit analysts, make them impossible to misfill. Surface the reporting period and required inputs on the first screen, lock formula cells, put input validation on every input column, move the cash balance and headcount totals to the top of the summary, and flag any missing or negative numbers with a red error cell and a short remediation note. Also produce a one-page guide that shows where to paste raw monthly extracts and what a clean upload looks like.

I built the Cash Flow template and pasted last month's extract into the data tab; the summary total is off by $48,200 and Jamie says it used to match. I am afraid I broke a mapping or a hidden conversion, and I cannot tell which sheet or which formula changed because multiple people edited the file. Is this likely a mapping mismatch or a formula override, and what exact steps should I take now to isolate the $48,200 discrepancy before escalating to Jamie?

Every month someone paste-updates raw extracts and we spend two hours re-fixing formulas, remapping accounts, and reformatting the summary. I keep losing time and credibility with the business leaders. What three changes should I make to stop rebuilding the wheel, prevent accidental edits, and get consistent, audit-ready monthly templates that the analysts will actually use?