Once your account is under our management, Motley Fool Wealth Management, in discretionary capacity, would be managing your money for you. That means Fool Wealth would make all the trades - you cannot transact in the account, nor can you tell us what securities to buy and sell. You will still be able to add funds, withdraw funds, restrict a few specific stocks, and disconnect your account from Motley Fool Wealth Management's authority.
Put simply, Motley Fool Wealth Management would have sole investment discretion over the course of our advisory relationship. So please note that we do not take investment instructions from our clients (although you do retain the ability to place or remove trading restrictions on specific securities in your account).
Interactive Brokers will be the custodian of your account, which means that they are responsible for the safekeeping of your assets - Motley Fool Wealth Management only directs the trading activity within your account and doesn't hold your assets directly.