Although not encompassing of all of the details, at a high level, this is how I keep them relatively straight in my head…
Current Account = Merchandise.
Capital Account = Non-Financial Assets + financial assets that migrants bring when they come to a country or take with them when they leave (This second part is the one that is tricky that is perfect for an exam question).
Financial Account = Foreign assets (Gov’t assets held abroad and Foreign-owned assets in the country).