Why can't I connect to American Express to link my American Express Personal account?

Congrats on your first post here in the Community forum, @hbpatrick43-gmai.

When connecting both business and personal American Express accounts, you need to connect them one at a time. 

Let me show you the step-by-step process:

1. In the left menu, click Accounting and choose Chart of Accounts. 
2. Tap the New button at the upper right hand to create an American Express Personal account.
3. From the Account Type ▼ drop-down menu, pick Credit Card.
4. Enter the account name, then hit Save and Close. 
5. After that, tap Banking in the left menu and select Add Account. 
6. Search and select American Express Personal Credit Card and pick Continue. 
7. Enter your American Express user ID and password in the pop-up window. 
8. Choose the accounts you want to connect in which you'll select the account created in the chart of accounts. 
9. Pick the date range for the download, then Connect. 

More details about this process can be found here: Connect your American Express Business account to QuickBooks Online.

For future help, you can visit these banking-related articles to help managing your transactions: Banking articles. 

I'm always willing to work with you again if you have other QuickBooks related questions. Just post them here. Have a great day!