If you come from the german quicken version and you want to export your quicken data, do not use quickens QIF export!
The QIF export is buggy and not useable.
If you have for a example a Wertpapier account (Depot), your activity with shares appear under the wertpapier account in the QIF file. But some (and only some) transaction also appear in the bank account.
For example: if you sell 1000 shares and you get 2000€, this transaction appears in the wertpapier account (depot). And maybe or maybe not it appears also in the bank account. kMyMoney tries to find those duplicates, but since the QIF file lacks a column with a unique transaction identifiert, this fails in many cases.
The problem becomes more difficult because such a transaction can be a splitted transaction in which case the amount in the bank account is not the same as the amount in the depot account. Example: you sold shares for 2000€, but your bank deducted 100€ tax. In this case, in your bank account are only 1900€, which a split into 2000€ for the depot account and -100€ tax.

The only way to export qour quicken data correctly is to create a report of the transactions. In the report settings, check the box to display all split rows and to use only 1 line for all memo fields (verwendungszweck). Then you can export this to a CSV file.