I use QuickBooks Simple Start. Is there restriction in the number of the bank account which can syncronise with Quickbook?

Happy to share details about synchronising accounts, @treasurer133.

There's no limit to synchronising bank accounts in QuickBooks Online as long your Financial institution is supported. That said, you can add one more account without extra cost. For complete steps, check out this link: Connect bank and credit card accounts to QuickBooks Online. 

If you can't find your bank when you search, check this link for possible reasons and how to submit a request: Find your bank or credit card account when you connect to online banking.

Moreover, don't forget to categorise the transactions and reconcile your bank account regularly. This way, your books is always accurate. 

Further, check out these articles below on how to fix some banking errors and manage your chart of accounts in QuickBooks: 

• What to do if you get a bank error or can't download transactions in QuickBooks
• Learn about the chart of accounts in QBO

Fill me in if you have more questions or concerns about connecting your bank accounts in QuickBooks. I'm always around to lend a hand. Take care.