Step 1. After logging into the Investor Portal, click on the 'Settings' tab:

Step 2. From the Settings screen, click on the 'Investing Accounts' tab. Then click on the 'Edit' icon next to the 'Linked Bank Account' field:

Step 3. A pop-up will appear with a drop-down menu. Choose the Bank Account that you would like to link to this Investment Account. Then click the 'Set Bank Account' button:

Step 4. Once that's complete, you'll see the new Bank Account listed with your Investment Account: