How do I add transaction from before setting up my account

Glad to see you here in the Community, @xtremewcw.

In QuickBooks Online (QBO), we can manually enter transactions. We can do it by clicking the Plus (+) sign, through the register, or on the transaction screen.

However, if you want to enter a transaction directly to the register, you can follow the steps below:

1. Go to the Gear icon.
2. Under Your Company, select Chart of Accounts.
3. Choose the account and then click View register.
4. Click the drop-down arrow below the Date column.

If you want to manually add bank transactions, you can use the WebConnect feature. You'll need to download the data first from your bank's website and import to QuickBooks Online.

I've also added this link about categorizing transactions in QBO: Categorize and match online bank transactions.

Don't hold back to drop a comment below if you have other questions. It's my pleasure to be of great help. Take care!