Accounts and connections
A Broker connection, a Trading account and a Protected account are three different things, and knowing which is which explains most of the product.
Three words that sound alike and mean different things.
Broker connection
One authorised link to cTrader - one cTrader ID, and the tokens that let Propcockpit act on it. Disconnecting revokes it. It can also fall into re-authorisation required, which means the venue has stopped accepting the token and only you can fix it by signing in again.
Trading account
One account at your broker, reached through that connection. A cTrader ID usually carries several. Propcockpit shows them masked - FTMO-••01 - and the raw broker id never appears anywhere in the product.
Protected account
A Trading account you have armed Risk rules on. Only Protected accounts are gated, watched and counted against your plan.
Disconnecting a broker does not delete a Protected account - it disarms it. The rules, the Initial capital and the history all survive, which is what lets you reconnect later and pick up where you were. While it is disarmed the cockpit says your rules are stored and not armed, which is exactly true.
Symbol universe
The instruments one broker quotes. Two brokers can use the same name for different contracts, so an instrument is only ever meaningful inside the universe it came from - which is why an account's watchlist is its broker's list, not a global one.