Hi there, @marusha3. 

Thanks for reaching out to the Community for support. I'm happy to lend a helping hand with merging your account.

The merging process will let the system move all your past transactions from the duplicate credit card account to the one you want to keep. Whenever you're ready, here's how:

1. If you're merging accounts that have reconciliation reports, save those reports first. The transactions remain on the merged account and stay reconciled.
2. Go to the Accounting menu.
3. Choose Chart of accounts.
4. Find the credit card account you want to keep. Then, select the dropdown arrow under the Action column and choose Edit.
5. Note the name and detail type of the account.
6. Check if the Is sub-account option is marked. If it is, take note of the parent account it's tied to.

You can see more details in Merge accounts, customers, and vendors in QuickBooks Online. 

Moreover, if you’re new to reconciliations or need more help, reach out to your accountant. This can get tricky and they know how to handle the next steps. 

Please don't hesitate to keep me posted on how it goes in the comments below. If you have other concerns about merging your accounts and managing transactions in QBO, I'll gladly help