How do I see who owes us money and for how long?

Accounts → Aged Receivables (/accounts/sales/aged-receivables): every outstanding sales invoice aged from its due date as at the date you pick — Current, 1–30, 31–60, 61–90 and over 90 days — across every organisation. Views: Summary (one line per customer per organisation, optionally grouped), By Company, By Customer (the group's true exposure to one party) and By Project. Expand a line for its invoices, or click a bucket for that bucket's. Outputs: PDF, Excel with formulas, CSV, email.