I need to change an account and the invoice is not updating with the new account.

Note that transactions in ConnectWise PSA are set up to use the accounts as they existed at the time the transaction was closed. For example, if the ConnectWise PSA  GL Setup Table has 1100 set for Accounts Receivable, then the invoice will be tagged with 1100 when it is closed. If you then change the Accounts Receivable account in the ConnectWise PSA  GL Setup Table to 1200, the invoice will STILL use the old account, 1100. To update a closed invoice to use the new account, set the invoice to an "Open" status, save the change, then set it back to "Closed" status, and save again. This will effectively "reset" the GL accounts against which the invoice is set.