Account & security
Yours, mine and ours: whose accounts are whose
Mark each account and transaction as Shared or as one person's, then filter by owner.
Once two people share a household, every account can be Shared or one person's. On Accounts, choose Edit owners and pick for each account; its transactions follow it. Countorra asks for this right after someone joins, and you can keep everything Shared instead.
A single transaction can belong to someone else than its account: open it and change Whose. To give several at once an owner, tick them on Transactions and choose Whose…. A rule can do it too, for example marking everything from the gym as one person's.
Accounts, Transactions, Reports and Cash flow have an owner filter: Everyone, Shared, or one person. Budgets, goals, recurring payments and the cash-flow forecast always show the whole household.
Nothing can be hidden: everyone in the household sees every account and transaction. When someone leaves, what they owned becomes Shared; nothing is deleted.
Where to find it