Hi accounts438.
Let me show you how you can upload your bank transactions.
If it is is an Excel file (XLSX or XLS), you can save it as CSV. Simply select the CSV (Comma delimited) as the Save as type.
You can also visit the Apps tab. From there, you can search for a third-party bank importer app or a file converter. Additionally, here's how to format CSV files in Excel to get bank transactions into QuickBooks.
Once everything's fine, you can now upload it into QuickBooks Online.
Keep on posting here if you have other questions. Have a great day!