I use quickbooks for 2 companies. One will connect with the bank and the other will not. They use the same bank.

Thanks for reaching out to us, dblanton012585.

I understand you use the same bank for both of your businesses. You'll be able to link your bank account to the company of your choice. I'll show you how.

1. Go to the Banking menu, then the Banking tab.
2. Click Link account.
3. Enter the name of your financial institution in the search field.
4. Ensure that you select the correct bank or have tried all possible link since some banks have multiple names on our list.
5. Select Continue, then sign in to your bank account with your user ID and password.
6. Follow the on-screen steps. This might include security checks your bank requires. It could take a few minutes to connect.
7. Select the accounts you want to connect, then select the account type ▼dropdown. Choose the account type that matches your chart of accounts in QuickBooks.

You can use the following resource to help you find your bank account when setting up for online banking: Find your bank or credit card account when you connect to online banking.

Once done, QuickBooks will download transactions from your bank automatically. Some banks allow you to download the last 90 days of transactions, while others allow you can go back up to 24 months. 

Additionally, only categorize and match transactions related to the company connected to online banking. Then, you can exclude a bank transactions that aren't included.

You can also manually upload bank transactions for your other company that isn't linked to your online banking.

I've also added this article for your future reference: Reconcile an account in QuickBooks Online.

Let me know if you have additional banking questions or concerns. I'll be around to help you.