QB Issue Resolution:
If you had saved the password before then it is in the Apple keychain. In the Finder open Keychain Access (its in the /Applications/Utilities folder or you can use Spotlight to find it). Once open, in the top right there is a search field. Type BankingAccountPassword. This will filter your key chain entries to just the banking account passwords for QuickBooks.
You should see one that says BankingAccountPasswordFor American Express with some other text next to it. Double click on that to open the edit window. Click on the Show Password checkbox. You’ll have to enter in your keychain password (its your computer log in password unless you changed it). Then you’ll see your old Amex password. Change it there and save the window.
Quit QuickBooks if it is running and then relaunch QB. Try downloading from Amex.
Resolution for Issue 'Changing password on credit card accounts?' available: Yes (Solved).
Source: Intuit Community forum.
Changing password on credit card accounts?: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.Support for Credit Card
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