Since my checking account is linked to quick book, would the items/ transactions in the checking account need to be entered separately?

I'm here to share some details about how online banking works, nellyaghili-gmai.
 

After linking your checking account to QuickBooks Online,  the program automatically downloads the latest transactions. Then, it looks for and tries to match them with transactions you've already entered into QuickBooks. If it can't find a match, it creates a new transaction record for you. All you have to do is approve the match or newly created transaction.

Here's how to add the transactions:

1. Find a downloaded transaction with the Add option in the Action column.
2. Select the transaction to expand the view.
3. Review the recommended Category. This is the account QuickBooks wants to categorize the transaction into. 
   For example, for a gas expense, QuickBooks may suggest categorizing it under Travel Expenses. You can always change the category and put it in a different account.
4. Change the vendor or customer as needed.
   Tip: If you think you already entered this transaction into QuickBooks, select the Find match option. Review the list of possible matches and select one if you find it.
5. Review and add any other information that may be mandatory or missing.
6. When everything looks good, select Add.

QuickBooks uses this info to create and add a new transaction to your accounts.

For more details about reviewing downloaded transactions and putting them in the correct accounts, please see these resources:

• Categorize and Match Bank Data in QuickBooks Online
• Set up Bank Rules to Categorize Banking Transactions in QuickBooks

To ensure the items are added correctly, I'd recommend checking out this article for reference: Create Products and Services.

Additionally, I've added an article that'll help you review your accounts in QuickBooks to make sure they match your bank and credit card statements: Reconciliation Workflow.

Please let us know if you need assistance managing your bank transactions in QuickBooks. We want to make sure your record is accurate.