Hello there, edfreedman1!
When you connect a bank or credit card account to QuickBooks Online (QBO), typically only the transactions from the last three months are automatically downloaded. If you need to import older transactions, you can do so by downloading them from your bank's website as a CSV file and then manually uploading them to the Banking page in QBO. This allows you to have a complete transaction history within your QuickBooks account.
Here's ab article to guide you through the process: Manually upload transactions into QuickBooks Online. You can then match and categorise your transactions after uploading them.
Feel free to go back to this thread if you other questions about your credit card transactions. Take care and have a good one!