Can I link a bank account to a cash account that already has a balance in it? The bank account does not match the cash account at all.

I won't rest until your accounts balances are fixed, @matt-hoel-geacom.

I've got here a couple of steps you can perform in correcting the difference between your accounts. Before we begin, allow me to provide you with a list of the possible reasons why the balances between accounts don't match:

• Outstanding transactions.
• New transactions for a connected account.
• Duplicate transactions.
• Edited or deleted transactions.
• Card (liability) account.

Here's how to resolve this:

1. Ensure that your opening balance is correct.
2. When confirmed, compare the balance with your real-life bank account.
3. Next, review your account register if this is the first time you'll reconcile the account, there should be only one entry (Opening Balance entry) that's already reconciled
4. If not, please follow the steps in this article: Fix issues for accounts you've reconciled in the past in QuickBooks Online.

I also recommend checking if there are any duplicate entries synced. You can simply delete them if you find one. 

Additionally, here's a helpful resource that you can access in managing your QuickBooks Cash account: Use your QuickBooks Checking account.

I've also attached this reconciliation guide that will serve as your reference in performing the process in the future. Once finished, QuickBooks will automatically generate a report for that session. 

If you have any other queries about fixing the balance of your account, feel free to post them here again. I'm just around the corner to provide help. Take care.