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If the last status of an account is “in arrears” and you settle it on that status, your credit score will take longer to improve. In terms of how long the information about your default payments stays on your credit record: The data retention period for default payments is 12 months.
So check your credit record after that period to see if it has improved. If not, then you can log a dispute with the credit bureau. If you see the problem is with a specific creditor you can log a dispute with the Credit Ombud.
Also, keep in mind that there are 4 major credit bureaus. TransUnion, Experian, XDS and Compuscan. It can be that some of the credit bureaus have not yet updated your profile.