Can I know how to connect bank account manualy and 1 account 4 account number

It’s nice to see here in Community, @darshini.
 
I see can that you want to create a parent account and set up each individual card as subaccounts beneath it.

Allow me to assist you with regards to your concern.

You should know how your bank sends the downloaded transactions before connecting to Online Banking. Only connect the parent account if the transactions download to one account. Connect the subaccounts, not the main account, if the transactions are downloaded to individual accounts.

Let's make first a new parent account

1. Go to Settings ⚙ and select Chart of Accounts.
2. Select New to create a new account.
3. In the Account window, select the Account Type ▼ dropdown. Then choose an account type. Note: if you see the New category window instead of the Account window, you’re creating a subaccount. If you need to create a new parent account, switch to accountant view.    
4. In the Detail Type ▼ dropdown, select the detail type that best fits the transactions you want to track. Learn more about detail types.
5. Give your new account a name. Tip: Use the detail type description to create a name that describes what you're tracking.
6. Add a description.
7. If this is a sub-account of an existing account, select Is sub-account and then enter the parent account. 
8. Now let's make sure the account in QuickBooks matches your real-life bank or credit card account. Choose when you want to start tracking your finances. In the Balance field, enter the amount in the account, and determine the as of date. Enter today's date if you want to start tracking immediately.
9. When you're done, select Save and Close.

Learn how to create subaccount in QuickBooks Online, see this article.

Furthermore, I’ve added you this link about organizing tour accounts for your references:

• Import your chart of accounts to QuickBooks Online
• Remove accounts you no longer use.

Let us know what your next concern in QuickBooks is. Have a good one!