I linked a credit card and have Assigned the transactions that loaded. NOW, can I pay the credit card bill w check and have these transactions appear on the check detail?

Let me guide you on how to create a payment for your bill, stfrancismil.

Generally, after you've entered the transaction, you'll have to write a check as payment so it would show on the Check Detail report. You can follow the steps below:

1. Select + New.
2. Select Check.
3. Choose the Payee from the drop-down.
4. From the Bank account drop-down, select the account the check withdraws money from.
5. Complete the check fields you need.
6.  You'll see the transaction you entered on the right side if you've already entered the transaction.
7. Click Add, then Save and close.

Aside from checks, you can also enter the payment as deposits or bank transfers. Here's how: 

To make a bank deposit:

1. Select + New.
2. Select Bank Deposit.
3. From the Account dropdown, choose the account you want to put the money into.
4. Select the checkbox for each transaction you want to combine.
5. Make sure the total of the selected transactions matches your deposit slip. Use your deposit slip as a reference.
6. Select Save and close or Save and new.

To record a transfer using check:

1. Select + New.
2. Select Check.
3. Enter the check as you normally would, including the check number.
4. From the Bank Account field, select the account the funds are coming out of.
5. From the Category column, select the account the funds are going into.
6. Select Save and new or Save and close to record the check.

This shows up on your bank transactions once downloaded. However, you'll have to run a separate report so you'll be able to view the transactions.  Furthermore, learn how to match transactions with what you've already entered in QuickBooks. I've got this article for your guide: Categorize and Match Online Bank Transactions in QuickBooks Online.

Keep in touch if you have any questions about paying a credit card bill. I'll always be right here to assist.