Credit card transaction files are granted in varied ways by different banks. Credit/Debit transactions are in most cases distinguished by positive amounts or negative amounts.
If this is also the case for your transaction lines in the .csv file, your import summary will look like this:
Should all Credit/Debit lines come up as positive or negative amounts, there will need to be some other setup in the import screen, to make sure this is reflected properly in the transactions in Expense.
Suppose your columns have a similar setup such as:
Then you will need to set the following in Expense:
More on credit card transaction import, see article: Credit Card Transaction Import