Hi Payroll17,
welcome back to the community!
Usually when a transaction which was previously a Bill/invoice in QuickBooks desktop has changed into a journal entry upon migration to QuickBooks online, this is because there was something wrong with that particular transaction in desktop itself which may not have been picked up by verifying the data.
If this is just one transaction we would suggest that you delete the journal which has been created, and recreate this transaction as a Bill in QuickBooks online.
Let me know if that works for you.